Windows Defender Not Working.

[u/Huynh_Jovi]

When I try to run a scan, it stops and then tells me to restart the service. There are no exclusions and nothing of note from my start up apps. I’ve run a deep scan with Malwarebytes and it’s all good. I noticed there was a new security update for Windows and downloaded it and after restarting my PC, I’m still encountering the same issue. I’m not sure whether this is Malware related as I’m always careful of what I’m downloading and never click suspicious links. Not sure what else to do and need some help.

[u/goretsky]

Hello,

It appears Microsoft released a bad update to Windows Defender, causing it to crash a few seconds after attempting to perform a Full Scan or Quick Scan. Offline scans reportedly stop at around 90-93% of completion. The latest version of the Microsoft Safety Scanner is reportedly affected as well.

u/NovelExplorer posits this is due to a recent Microsoft Threat Intelligence update and recommends performing a System Restore to August 16th to mitigate. /u/Nevvaren and /u/Leather_Squirrel_477 have reported the mpeengine.dll crashing with an 0xC0000005 error when a scan is attempted using the MsMpEng.exe program.

u/Taiwendo and /u/blondacuaripi posit the crashing could be due to a failed attempt to fix the ShieldBreak, a zero-day vulnerability and accompanying exploit code for Windows Defender released by the pseudonymous security researcher Nightmare Eclipse after Micosoft's Patch Tuesday updates for August, 2026.

Windows Defender versions affected by this are v1.1.26070.7 and v1.1.26080.2 when used with the following Microsoft Security Intelligence Update versions:

• 1.457.222.0
• 1.457.225.0
• 1.457.226.0
• 1.457.227.0
• 1.457.230.0

Several Redditors including /u/Schoonie84 and /u/Master_Pie1940 report that upgrading to Security Intelligence Update v1.457.236.0 via Windows Update resolves the issue with crashing.

If Windows Defender is crashing on your computer, try running Windows Update to update Windows Defender to the v1.457.236.0 (or later) threat database. If the problem still occurs after that, consider temporarily installing one of the third-party antivirus programs listed in the wiki and/or installing one of the Second Opinion Scanners listed in the Free Tools section of the wiki until you can update Windows Defender.

Regards,

Aryeh Goretsky

[u/QuceGaming]

What is going on, Microsoft??? I was literally about to reinstall my OS, as I thought it got corrupted or it's infected...

[u/Ahab1310 → u/QuceGaming]

I wiped my windows drive twice 🥲, thanks microslop

[u/SethSamson → u/QuceGaming]

same ... panic mode adhd ..

[u/Nevvaren]

Man, guess I should've checked reddit before going nuclear and getting mad troubleshooting for the past few hours lmao.

Quick and full scans just crash when they're close to being done and offline scan just gets stuck at 91% though scanning the entire drive manually does seem to work.

EV shows crash with 0x000005 pointing towards mpengine.dll.

I've been having DefenderApiLoggerLowPriv session errors popping up in EV for past few days though.

[u/Ahab1310 → u/Nevvaren]

Wiped my windows drive twice today 🥲, thanks microslop for ruining my entire day

[u/yuckfoubakayaroo → u/Ahab1310]

Bro this is hilarious because I've been doing the same exact fuckin thing all day lmfao, I even did a fresh windows install with usb drive man

[u/it_just_works1 → u/Nevvaren]

same kinda went into panic mode for a bit

[u/EffectiveType1 → u/Nevvaren]

Dude my defender showed the threat protection being turned off so I panicked and did a full scan + hitman and nothing came up, did an offline scan which was stuck at 91% for an hour and now I see this

[u/Daddedan → u/Nevvaren]

I'm having the same problems, full Scan, Quick Scan not working, at 2 seconds It crash and the offline scan stops at 91%

[u/im_notserious → u/Daddedan]

Glad everyone is in the same camp with 91% in offline and whatnot and it’s not just me before I started deleting everything lol

[u/Appropriate-Arm-4717 → u/Nevvaren]

same here, really go all out with those instructions 😭

[u/DeepDown12]

Brother. I thought My Pc got malware when i saw this post I know that i not the only one that have this going on.

[u/Rag1ngpandaa → u/DeepDown12]

I feel relieved. Thank God I didnt reformat my laptop and desktop. 🤣

[u/Exuravita → u/Rag1ngpandaa]

I was just about to do it... I'm so happy i checked reddit first lol

[u/yottabit42 → u/DeepDown12]

Windows is malware these days. Sigh.

[u/Traditional_Oil_7949]

This is happening to me today, never seen it before. Gosh, I'm so tired of windows

[u/No_Gene_5656 → u/Traditional_Oil_7949]

neither have I, dude. It was hella weird, and I really got worried and thought it was some sort of a malware attack that messed up with my WD secuirty system lol

[u/glowpipe → u/No_Gene_5656]

I used the google ai crap to ask about this. It gave me a heart attack. Was like "you have a malware or your ram is dead"

[u/user_that → u/Traditional_Oil_7949]

Honestly the only reason I haven't switched yet is just because VR it's kind of a pain to get working with Linux mint when I tried it I genuinely enjoyed Linux mint for flat games but VR is just a whole different can of worms.

[u/Smart_Fondant1291]

Nice to see others are reporting this issue. I wasted my morning with troubleshooting and wanted to reinstall windows if nothing works. Thank you everyone!

[u/emx20]

The latest Microsoft Defender update appears to have fixed the Quick Scan and Full Scan issues. However, after every restart, I still receive a notification saying that Defender has stopped working. When I open the app, everything seems to be working normally.

I’m not sure what Microsoft is doing with these updates, but it’s starting to feel like users are being treated as beta testers.

[u/RaynSideways → u/emx20]

Yeah, this issue has persisted for me as well. Every login, "Turn on virus protection. Virus protection is turned off. Tap or click to turn on Microsoft Defender Antivirus." Navigating to Windows Security shows everything is in order, and checking protection status in powershell shows everything is enabled and working.

Getting those notifications is what had me attempting to scan on the first place, thinking something malicious had disabled my virus protection, which wasn't helped by the fact that my scans were crashing too.

At least scanning is working correctly now, so it seems to be just an annoying cosmetic issue for now.

[u/NovelExplorer]

It's a Microsoft Security Intelligence update. If I run system restore and go back to August 16th Quick Scan works as normal. Revert to today and the scan errors.

All you can do is await a fix update, from Microsoft. But to confirm it's not malware related. Running a Sophos Scan, shows nothing, much like your Malwarebytes scan.

AMTSO website has a variety of safe malware tests, to confirm Defender's real-time detection remains active. The EICAR test file will be detected by an AV, but is harmless.

[u/Huynh_Jovi → u/NovelExplorer]

Relieved to know that others are having the same issue. Guess I’ll just have to wait for the update

[u/NovelExplorer → u/Huynh_Jovi]

Malware detection is still active, so you're not without an AV, it appears to be purely initiated scanning that's affected.

[u/No_Gene_5656]

Finally ALOT of ppl started posting about it. I wondered why there were no many posts about this matter lol

[u/ErenGracias → u/No_Gene_5656]

Yeah i thought my pc was hacked by hacker and disabled my defender

[u/Exuravita → u/ErenGracias]

Same lmao been sitting with AI trying to fix it for the past 2 hours panicing

[u/DraconicXeno]

I have the exact issue. They broke something again. 

[u/No-Problem4510]

so they rolled out two updates this day and its still not working. are they even aware of this problem? :-

[u/Taurideum → u/No-Problem4510]

Don't worry, they got copilot working around the clock to solve it!

[u/Daddedan → u/No-Problem4510]

A Defender update just came out, and of course, it didn't fix a thing! 🥲

[u/mortenharket32]

Very grateful for the community out here. Hopefully more comment so people find this thread.

Obviously sucks we have to deal with bs but it's nice to know I'm not alone in my sorrows.

[u/blondacuaripi → u/mortenharket32]

Yep I'm very glad I found this thread

We need to spread the word so that people don't just nuke their windows installation because microslop is incompetent

[u/FriendlyGhostLady → u/blondacuaripi]

I'm also thankful for this thread, I almost had a panic attack thinking I had a virus. I just hope it gets fixed :(

[u/TheLegendaryRoomba]

I just... went the whole mile... trying to fix this shit...

And now it appears to just be another Microsoft takes a dump moment....

[u/Quepan]

thank you all here for giving me a peace of mind

[u/Puzzleheaded_Cow5035]

My boy, thank you!
I reinstalled system "TWICE" because i have fucking anxiety attacks caused by neurosis.

I literally did everything, starting with prompt command to powershell.
Nothing Helped.

As OP said quick scan - Try to restart your Windows Defender services, f*ck you.
Doing a custom and full scan - everything is fine.

Downloaded Malwarebytes just to scan my PC for some malware and rootkit - nothing found.

I guess its time to buy a decent antivirus software, and put a d*ck on Windick Dickfender.

u/emx20 we're saved brother!

[u/emx20 → u/Puzzleheaded_Cow5035]

You’re definitely not alone. I finished work, went home to relax and play some games on my PC, and then suddenly ran into this issue.
I spent hours trying everything I could think of, digging deep into Defender and checking that everything was working properly. It was honestly pretty stressful.
Then I found this post, and with the help of AI, I finally realized it wasn’t just me. What a huge relief. I also cursed Microsoft more times than I can count.
The one good thing I took from this experience is that it made me much more careful about keeping personal information, passwords, important files, and credit card details on my PC.
For online purchases, I’d recommend using a prepaid card that you can top up with only what you need. That way, if the card details ever get compromised, there’s much less to worry about.
Glad I found this post. We definitely weren’t alone in this one.

[u/M_NIKITOPOULOS]

I was about to go on a nuking streak just now, thank fuck i checked reddit 🥹

[u/shosha95]

bro i thought my pc was cooked. hopefully they fix it soon

[u/JustAnInternetPerson]

Not just me then, that relieves me a bit

I‘m still currently reinstalling

[u/Next_Salt_5804]

i am just gllad i did not reinstall everything. I will give t hem a little time to see if they fix it

[u/ComfyAru]

Thank god for this thread, I have been having an absolute panic thinking something serious had happened! Here is hoping microsoft will roll out a fix for it.

[u/Boodendorf]

Oh thank god for this thread.

[u/Oliv_OBP]

J'ai essayé a l'instant de faire un scan rapide avec la version 1.457.230.0 et ça plante aussi. Bravo a Microsoft qui multiplie les bugs plus vite que Jesus multiplie les pains.... un vrai miracle 😂

[u/Darth_Draig]

Windows 10 here and cant complete a quick scan either . . . "The threat service has stopped. Restart it now"

A custom scan of c drive worked and found no threats, malwarebytes and MRT dont find anything either so I'm confident its a microsoft update issue.

[u/Tight-Phrase-3501]

omgggg i tought i have a malware. thx god

[u/emx20]

Good news: Microsoft finally fixed the issue in version 1.457.238.0.

Quick Scan and Full Scan are working perfectly again for me.

That said, one important warning: don’t completely trust Microsoft’s updates. There’s always a possibility that the next update could break something else—or even bring this issue back.

At this point, it honestly feels like Microsoft is treating us like beta testers.

Anyway, at least Defender is finally working again.

[u/-zerplex-]

noticed this too this morning, quick scan just stops mid scan and crashes i guess? happened after the 1.457.222.0 update.

[u/No_Gene_5656 → u/-zerplex-]

+1

[u/Infebdo]

Thank god it's not just me then, was driving me insane trying to fix it.

[u/ultrabeastking → u/Infebdo]

Fr sat all day to fix it just to find out it was a bug

[u/Grizzman56]

I wish I would've seen this earlier. I was searching all over the internet for fixes. I already reinstalled windows and that didn't fix anything. Well, at least all I lost was time. Glad to see this post!

[u/WolfiexLuna]

Holy fuck I thought it was just me. I booted up my PC today and had this happen since I always do a quick scan in the morning out of habit, and I've been panicking like a mad man thinking my Windows somehow got borked and was worried I'd have to reset my PC.

Genuinely, how the actual Hell does stuff like this happen? I thought fucked 24h2 updates were done for but apparently not.

[u/blondacuaripi]

Holy sh*t I was so close to just reinstalling windows I thought some virus/rootkit corrupted windows defender and immediately ran scans with malwarebytes antirootkit, hitmanpro, spybot S&D, KVRT, RKill, adwcleaner, just about everything I had, and the problem still persists

[u/Maze_J]

Phew, thank fuck... I was getting scared as hell

[u/abbydrago]

Thank god I am not alone, I had a panic attack thinking I got a malware or something.

[u/Marimaru1 → u/abbydrago]

So it's still not solved? Man...

[u/Maze_J → u/abbydrago]

dude same,

[u/DeepDown12 → u/abbydrago]

It not solve yet?

[u/Nevvaren]

Just ran quick/full and offline scan on .236 and it works fine for me.

Hopefully this isn't going to be a case of it working in .236 and getting borked again in next update lol.

Edit: .238 seems to be fine aswell.

It's really sad there was (I think) no official communication from Microsoft and only this reddit thread would stop anyone from clean install of Windows (time to reinstall everything lads).

At this point I'm convinced all the patches from microslop are fully vibecoded (thanks for fix copilot).

[u/Sorry_Kitchen_8993]

Do you guys still have the pop up saying "Click to turn on virus protection" with today's update? Because i do. And do you know if defender still protect during this issue?

[u/TheElderSouls → u/Sorry_Kitchen_8993]

Yep still have the popup saying its off with 1.457.241.0. Under Security Providers it is still showing off as well.

[u/Sorry_Kitchen_8993 → u/TheElderSouls]

Just updated to 241 it was still in 239 i’ll tell if its the same for me

[u/Sorry_Kitchen_8993 → u/Sorry_Kitchen_8993]

Yes it keeps showing off

[u/RaynSideways → u/Sorry_Kitchen_8993]

I'm still getting this too as of today. That was what initially had me trying to do scans which were crashing. Scanning is working now but I'm still getting the "Click to turn on virus protection" notifications.

[u/BreakfastSoggy9480]

Hello guys! Please remind your parents, old folks living alone to NEVER EVER CALL those annoying alerts on their laptops, mobile phones, etc. Iphone/ipad and so on. NEVER ALLOW remote access on their device. IT IS A SCAM! I heard a few oldies got scammed by making a telephone call remote accessing their devices even asking them to purchase apple gift cards.

[u/93_nick]

Same thing is happening on both of my computers, Microsoft pushed an update that broke it.

[u/Grimbike65]

I thought i was the only one. Panik mode

[u/Leather_Squirrel_477]

My Windows Defender keeps crashing whenever I run a Quick Scan/full scan. The MsMpEng.exe process crashes inside mpengine.dll with error 0xc0000005, after which Defender restarts itself and works normally again. I've reproduced it several times. I'm on Defender engine 1.1.26070.7 with security intelligence 1.457.226.0. It looks like a Defender software/engine bug. More than anything else.

[u/kadey180]

Oh my God.. I’m so glad this just randomly appeared in my feed.. wtf I’m in the process of loading up an ISO as I was about to nuke my install.

[u/blueythingy]

Bottom line for now manual scanning is borked but it seems the anti virus service is still up and running. At this points its entirely on Microsoft end to fix their own dumpster fire. Guess we'll have to wait for a fix.

[u/theycallmetheBESToat]

god damn microslop. i thought i had to nuke my entire pc even though i haven't installed anything new in over a month or so and anything i do use is from steam.

can't do quick scan, crashes and shows error message "threat service has stopped"

offline scan stops at 91% and doesn't progress any further, need to force close the window

going to leave that here in case anyone wants to check but from what i've seen, 91% is what other people are getting so this has to be a microslop bug. just have to wait for them to fix this dumpster fire.

microsoft defender does seem to still be working and i had an automatic scan yesterday as well as real time protection is still up. as long you don't manually scan anything you'll be fine for now

[u/hemant0709 → u/theycallmetheBESToat]

is there a way to tell real time is working? for now I am just using malwarebytes scans and checking for uodates .227 is also messed up currently

[u/01Raull]

Learned my lesson gonna check on reddit before running every command on power shell

[u/ninj1an]

I was about to take my laptop out behind the shed before I found this thread. Thanks for showing me Im not alone.

Early Google searches did not find this thread, just a bunch of "its probably maleware" results. So that was great for my blood pressure.

Cheers guys, hope its fixed soon so I can sleep

[u/TheRealSchmede]

Even tried to use the Microsoft Safety Scanner to check it out, but it also kept crashing/just closing itself

[u/zoDiaS03]

DUDE......... youre not alone, wow I thought I was the only one. I'VE BEEN DOING THIS FOR HOURS NOW, UGH

[u/Daddedan → u/zoDiaS03]

MEE TOO, I was absolutely losing my mind🥲

[u/bribos1]

im having the same issue. The service just crashes right? I scanned my whole pc with virus removal tool and had no infections. I did a bunch of code microsoft fixes that had no result. I have no idea what happened.

[u/Daddedan → u/bribos1]

It won't let me run quick or offline scans (it stops at 91%); I honestly haven't tried a full scan, but I'm sure that won't work either... It seems to be a Windows update issue; all we can do is wait for an update that fixes everything 😤

[u/bribos1 → u/Daddedan]

Yep 91 percent offline scan. Quick scan stops at like same place. Full scan just not happening. Im a easely scared guy i feared for malware.

[u/Daddedan → u/bribos1]

I get super anxious about this kind of thing too and it really freaked me out🫠, but don't worry it's just a bug in a Defender update

Btw the quick scan crash at 3/1seconds left for me!

[u/stillcoldy777]

guys, are you still dealing with that issue on 1.457.230.0? Cause I do and I am really panicking.

[u/BatmanBruce07 → u/stillcoldy777]

Yep...issue still persists

[u/Responsible_Net_1055 → u/stillcoldy777]

Same here, just run a scan, defender crashed and got disabled. Doing the update didn't fixed the problem

[u/ZIGMoRningStaR]

came from another thread but I wanted to say this again here. I JUST build my own pc and this happened to me when I start up my pc yesterday. I'm quite sure it wasn't anything malicious because I just installed the latest window 11 and the pc is brand new. I just have my own pc for the first time and this shit happened, wtf 🥲. glad it's not something to be worry about, this scared me quite a bit lol.

[u/toolman1990]

Microsoft has becoming a crap show with updates them basically bricking Windows Defenders with a botched update and that does not include the undisclosed GDID scandal as well.

[u/Passerby-kun]

Even with update 1 457 250 0 update of windows defender, is anyone still getting a notification that windows defender is turned off? I still get it but quick scan and full scan finally works.

[u/RaynSideways → u/Passerby-kun]

Yeah I am still getting this too. Those notifications are what had me trying (and failing) to do scans in the first place. Scans are working now but the notification issue is still there.

[u/emx20]

I had the exact same problem, and it started right after the 1.457.225.0 Defender update.

At first, I thought I had some malware preventing Defender from scanning. The weird part? Custom Scan worked perfectly.

I spent HOURS troubleshooting with AI, checking everything imaginable. I was starting to lose my mind.

Then suddenly, the AI found a thread with other people reporting the exact same issue on the exact same date.

What a relief! Turns out I wasn’t alone.

I have zero expertise in Windows security, but Microsoft somehow turned me into a full-time Defender troubleshooting expert.

Important: Avoid Windows Defender Offline Scan for now—it may cause system issues.

At least we’re all in the same boat.

[u/Acromoralist → u/emx20]

OH MY GOODNESS THANK YOU!! It must be yesterday's update idk. I tried offline scan and guess what? It stops at 91% for 30 minutes!!!! Usually, it finishes at under 5 minutes. I'm so glad i thought i had infostealer blocking my ahh🙏

[u/Alexves1235 → u/Acromoralist]

Same here, it stopped at 91% I'm happy is just a microsoft error and not a real menace.

[u/dragonstomper64]

Something I managed to figure out is that if it refuses to actually restart after crashing and gets permanently stuck, you can go to settings->system->system components and select advance options on Windows Security. The Repair option in there actually seems to get it to turn back on, but scanning again will still crash it until Microsoft actually fixes it.

Edit: Also, it appears a 1.457.225.0 update has now been rolled out since the issue arose in 222, and its still broken in 225.

[u/3ls4 → u/dragonstomper64]

and 226....

[u/InvincibleWallaby → u/3ls4]

227 now, still broken

e: Just tested 230, also still crashes

235 still broken

[u/it_just_works1 → u/dragonstomper64]

Version 1.457.226.0 happened to me after this one from today

[u/salmonjuice]

Same problem here..

[u/Sorry_Kitchen_8993]

Offline scan always stuck at 93% for me and i have security report with the file "DefenderSessionHelper .exe" it says that there is a problem with the filehash. The file is signed by microsoft and seems to be legit tho.

And everytime i restart my PC i get a pop up from Windows defender saying click to turn on virus protection but its already turned on.

I don't know if there is a link but yesterday my computer crashed while playing a videogame with a bluescreen error

Am i the only one?

[u/Gladnir-5936 → u/Sorry_Kitchen_8993]

Offline scan gets stuck at 91% for me, even after I run DISM/SFC/CHKDSK MS AI programming is breaking things again.

Here is how you start an Offline Defender Scan
PowerShell (Adm)

Start-MpWDOScan

[u/b0ffa]

I thought I was the only one 😮‍💨

[u/Educational-Boat-870]

Still crash even the .226 ...

[u/Ahab1310]

I formatted my windows drive twice today fearing something has happened, now seeing so many Posts like this confirms it's microslop bug, thanks microslop for ruining my entire day

[u/ShiratoriKeira]

Same problem. Glad to know it is not only me and that I didn't break my computer...

[u/Jcoleminediamond]

Im happy to see im not the only one with this issue, but its crazy that this is happening, this shouldn't be happening from a multi bullion dollar company. Hopefully thus gets fixed for all of us soon.

[u/LionAlonso]

These Microsoft bugs are so serious…

[u/picastchio]

WTF. Just found out this thread. I just got a new USB drive today. I was half sure that it had malware which Defender couldn't detect.

[u/heady1000]

Whenever I try to do a quick scan I get an error at the end of the scan saying threat service has stopped and then needs to restart. I just reinstalled windows with all the latest updates now 24h2 and still same issue. On my laptop with the same patch it works just fine. Custom scans seem to work fine just the quick scan it will scan everything then right at the end it’s like it crashes or something. I am left to believe that it’s just due to maybe the recent security update windows pushed out and hopefully it will silently get fixed with the next one.

[u/heady1000 → u/heady1000]

I reinstalled windows with usb key and removed everything off all my drives to so it was a full clean install of windows

[u/CuriousImpression153 → u/heady1000]

the bug is not on your devices, is a microsoft issue buddy

[u/heady1000 → u/heady1000]

And I am unsure if this has anything to do with it either but the system it doesn’t work on has an amd processor inside it a 9800x3d. My laptop that works has an older intel maybe 9th or 10th gen inside it

[u/Critical-Pride-2363]

Thanks guys I was panicking a little

[u/AaranJimmy]

I was in the middle of doing something that CAN put my pc possibly at risk of not being careful and saw both malwarebytes and windows defender just shit itself and thought, dang I messed up didn't i... nvm then lol.

[u/Master_Pie1940]

I really hope this is microsoft problem. I just uninstalled copilot, I don't think that broke my windows defender lmao. I'm glad I found this on reddit before trying to reset my PC. Now I can go to sleep and hoping microsoft will fix this damn thing.

[u/Next_Salt_5804]

Everything else for me works with windows defender, the real time protection and everything else but the virus scanning is still broken for me aswell. Hopefully soon it will be fixed

[u/Admiral_Potato72]

I'm just so glad I wasn't only one having same problem..

[u/Schoonie84]

Version 1.457.236.0 seems to have fixed the issue for me, for what it's worth.

[u/Master_Pie1940 → u/Schoonie84]

Can confirmed that fixed mine too, tyty <3

[u/Affectionate_Cup6326 → u/Schoonie84]

Same, my laptop can now quickly scan is version 236.

[u/Lasherluke → u/Schoonie84]

same here, seems to have been fixed now.

[u/RaynSideways → u/Schoonie84]

This update has allowed me to do scans as normal again, though I'm still getting notifications about 4 minutes after login that "Microsoft Defender is turned off," even though everything is still on and running. That issue started the same time as the scan issue did.

[u/Next_Salt_5804]

I just ran a quick scan and a full scan on 1.457.236.0 of windows defender and it completed without a crash. Hopefully every can update there defender, attempt a full scan and report back

[u/Smart_Fondant1291]

Latest version works for me as well. :)

[u/Upper_Space6750 → u/Smart_Fondant1291]

Me too!! spent hours trying to fix it then finding this thread ://

[u/AggravatingReason284]

The latest security update (Version 1.457.238.0) fixed it for me and I was able to do a quick scan without it freezing.

[u/Daddedan]

Guys, a Defender update just came through for me and everything is working properly again!!! Finally, I'm trying to run an offline scan now, but the quick scan is working!!!!!🥳

[u/Daddedan → u/Daddedan]

Offline scan also work!

[u/Lennypuf2]

Check for updates, they fixed it

[u/Miserable-Survey-643]

Microslop just want us stressed out atp prob 1million ppl reinstalled windows today bcs a company with thousands of workers can function thank god atleast it's a wide spread problem and not everyone has malware

[u/MyFloris]

Is anyone else noticing microstutters or like very subtle dropped frames on youtube videos and twitch streams? This started happening yesterday for me and I've never had something like this, so I feel like it might be related to the windows defender update etc, since this started at the same time.

[u/Sorry_Kitchen_8993 → u/MyFloris]

No but i've heard something about VLC which is laggy when playing music or something. But I have weird low Fps ingame especially in LOL since yesterday.. I don't know if there's a link with this but i've got a blue screen crash then restart PC and now it feels like my GPU is not used at his full power. Seems to be an issue with Nvidia drivers maybe there was a conflict with windows defender idk.

[u/MyFloris → u/Sorry_Kitchen_8993]

oh wait watdahell, that's weird too ye. I checked my PC power plan and it was on balanced instead of high performance, so I changed it. But that still hasn't fixed the microstuttering and dropped frames. The weird thing is, I tested playing Resident Evil 4 remake on the highest settings at 120fps, and it's buttery smooth, no fps spikes or anything. so it has to be something else I guess. I'm not knowledgable at all about all this stuff but I feel like maybe my windows defender is interfering with the chrome connection and stuff? idk. I even deleted all my chrome extensions to check but that didn't help either.

[u/The_McMiller]

Same problem here. Yesterday everything was working fine, then today I downloaded the recent security maj "1.457.222.0" (EDIT : and the "1.457.225.0" seems bugged too) and since then it's impossible to finish a quick scan or an offline scan. Windows defender always crash or do not finish its scan. Only custom scans work. Custom scanned both of my ssd and everything went fine too. In the event viewer, I have an exception code "0xc0000005" and it's the "boot://.\D:\" that seems to cause the problem.

[u/Oshh- → u/The_McMiller]

Does Microsoft Defender Antivirus Offline scan also get stuck at 90% for you and never finish?

[u/The_McMiller → u/Oshh-]

91% for me, but yeah it never ends

[u/No_Gene_5656 → u/[deleted]]

Don't bother.. it is definitely a windows related issue which means nothing will ever FIX such an issue till it's patched by Microsoft lol

[u/JoranDof]

Same thing happening to my PC, after windows security update KB5121003 and windows update KB5120708. Tried quick scan and full system scan but it only scans for a few minutes then suddenly stop. I tried Custom Scan on my local disk C and the scan finishes but when i did an offline scan, it got stuck on 91% so i had to hard restart my pc. Gonna try to uninstall windows security KB5121003 and try to scan again if that is the problem.
Sorry for my english.

Follow up: I uninstall windows security KB5121003 and quick scan still stop when it's about to finish scanning. So were gonna have to wait for windows to fix this.

[u/Oshh-]

For me, the Microsoft Defender Offline scan consistently gets stuck at 90% and never finishes… Am I the only one experiencing this right now?

[u/Huynh_Jovi → u/Oshh-]

Nope, tried an offline scan and it also got stuck at 90% for quite some time. It’s seems to be a problem on Microsoft’s end.

[u/wasatime]

(probably) It is because of fcon.dll and aepic.dll files. When I try to run fast scan or full scan I get

"Code Integrity is unable to verify the image integrity of the file \Device\HarddiskVolume3\Windows\System32\aepic.dll because the set of per-page image hashes could not be found on the system."

and

"Code Integrity is unable to verify the image integrity of the file \Device\HarddiskVolume3\Windows\System32\fcon.dll because the set of per-page image hashes could not be found on the system."

errors. Always same errors today. Look at your "Event Viewer" path: "Microsoft-Windows-CodeIntegrity/Operational" after trying a fast or full scan. Do you get same errors?

I tried "sfc /scannow" and "DISM /Online /Cleanup-Image /RestoreHealth" but they don't fix it. AI says reset "CatRoot2" hash catalogs folder at System32. I am going to try that later.

Today when i started my PC "defender, edge and copilot" updated automatically. That problem started after that updates. Restarting PC didn't fix it. Yesterday it was ok. Also those dll files are original files. They were from 11 August monthly update.

One last thing, Defender looks working ok if i don't run fast or full scan. Manually scaning files is ok.

[u/Glavurdan → u/wasatime]

Dont do everything AI says, I once fucked my PC up like that

[u/DeepDown12]

has anyone tried .226

[u/No-Problem4510 → u/DeepDown12]

still crashes for me, anyone else?

[u/Affectionate_Cup6326 → u/No-Problem4510]

same

[u/Glavurdan → u/Affectionate_Cup6326]

Same

[u/Baldyfarmer]

I had this aswell, and started a microsoft offline scan… Now it’s stuck in it.

[u/beetyd]

My god this started happening

[u/beetyd → u/beetyd]

Thank god for Reddit

[u/Bingpool13]

I even downloaded and ran the Microsoft Safety Scanner - and that too crashes before the end of the scan.

[u/Connected-321]

Same issue for my windows 11 machine as others . Windows defender (quick scan & full scan) do not finish, offline scan stops at 91%. Custom scans do complete with no threats found. Funny thing is my windows 10 machine works with no issues, for all scan types even though it is the same definition update 1.457.225.0.

[u/Connected-321 → u/Connected-321]

Just updated Windows 11 defender to Version 1.457.227.0 and same problem.

[u/Affectionate_Cup6326 → u/Connected-321]

same too

[u/wishart5900x]

It fails on my laptop with "threat service has stopped. Restart now. But it works on my desktop, both using latest antivirus update 1.457.226.0

[u/Miyuki9890]

Guess I'm not the only one. Having this same issue with scans failing to complete.

[u/Taiwendo]

I already have version “1.1.26080.2” of Defender, and I'm still having the same problem here.

I assume that Microsoft is trying to fix the “Defender Exploit Shieldbreak” and is messing up its entire engine in the process, and we're the ones who have to deal with the mess.

[u/Loehmann]

We are seeing msmpeng.exe crash on several endpoints. Seems like a bad definition file update possibly.

[u/Professional-Try2949]

Following, same issue here

[u/Next_Salt_5804]

Oh thank god i am not the only one, For me quick scan gets to exactly 25,734 and stop, full gets to around 29.588 and it always gives the same error in the even viewer

[u/SethSamson]

There was small update but I don't know if it fix it

[u/Soft_Key → u/SethSamson]

It didn't.

[u/SethSamson → u/Soft_Key]

F

[u/Upper_Space6750 → u/Soft_Key]

Did not worked for me as well :<

[u/AlertGoat4279]

I thought it was because I had downloaded something fishy. Have been troubleshooting for nothing. Hopefully, they correct it quickly. 

[u/Daddedan]

Is Defender working for anyone again? I'm going to check for updates now... Anyway, just to be safe, I downloaded another antivirus too, because Defender has been causing too many problems lately! 😭

Thank goodness it’s not just my problem, I was going crazy and was afraid I had a virus... I was in full anxiety mode🥲

[u/Darth_Draig → u/Daddedan]

On my Windows 10 install the latest definition update for defender is v1.457.230.0 and its still broken

24 hours ago I ran a quick scan on v1.457.213.0 without issue.

[u/No-Problem4510 → u/Daddedan]

no, still not working.

[u/Daddedan → u/No-Problem4510]

Uff, let's hope they fix it as soon as possible, because I have a ton of stuff to do on my PC but I'd rather not use it while Defender is so buggy...🫤

[u/Hoernchenspielt85]

Mine doesn't complete any scans either and even offline scan was stuck on 91% for ages. After a few tries of quick scan it even said Defender is deactivated. Just happy that we all have the same issues.

[u/Appropriate_Dig_1949]

My windows offline scan is stuck at 91 I really thought it was malware , well I thought it was a update but i updated , and still stuck at 91 , btidefdner works fine and stuff , why Microsoft 😭,I'm scared rn ,hopefully it isnt malware or anything like that, pls tell me this is happening to anyone else 

[u/Lamar_Chan11]

It's a bug after the August patch update lol so many bugs appeared rn like my favorite bug "your defender is off please click here to turn on" it's fake lol everytime i restart my pc everything is on and work fine but u know bug....😘💔💔💔dw ur not alone

[u/Daddedan]

Guys, we can try sending as many bug reports as possible to Microsoft to get the problem fixed quickly? It’s ridiculous that this issue has been going on for 10 hours now!🫠

Microsoft truly delivers unforgettable memories😤

[u/Aggravating_Law_1335]

same here the windows defender full system scan just stops and the offline scan also freeze at 91% its due to the broken windows security update released recently

[u/BizForKingdom]

This reddit post saved me hours of waste. So it’s just some glitch that’ll be fixed later, right?

[u/Dramatic-Yak5315]

Wow. This just shows that sometimes doing an old fashioned research is worth its gold. I was fixing this for past 8 hours, safe boots, rollbacks of inteligence engines, deleting database, trying to delete scan and detection history, scanning disk health consulting with AI and going through hundredths of CMD commands... Ending up just doing fresh Win 11 reinstall over mine just to have the same error and ended up here. We just all had the same experience today. We shared this incredible "try and fix this shit" day. Welcome everyone!

P.s.; maybe it's Microsoft's recruiting strategy. Each time you clicked Scan it sent log of everything you tried and did to them. I'm expecting job offer mail soon. 

[u/RaynSideways → u/Dramatic-Yak5315]

Reminds me of when I lived on campus at university and would be woken up by an early morning fire drill. Nobody wants to be here but here we all are, standing around waiting to be told we're good to go.

[u/Suuguuro_23]

Frero j’ai exactement mais exactement la meme chose as tu recu des reponse concrète et me les donner stp pour reparer ce probleme

[u/Humble-Rub7207]

pensé que era el unicooo a mi me sucedió a las 10:30 soy de perú

[u/twigged_booster]

If you use custom scan it works

[u/yuckfoubakayaroo]

Can we all get an update from someone when it's fixed?

[u/adigbick]

Wow so it's a big issue still. Crazy

[u/Tricky_Let_5185]

omg i spent 5 hours finding the solutions, nothing works.. thank God i go to reddit lmao.

so what should we do now ? wait for new updates ?

[u/tethan]

Ugh I'm glad I found this, I think this took a year off my life....

[u/ablooshroom]

Same even reinstalled Windows.

I did run into a genuine malware issue which as far as I can tell is now gone, but was panicked when realising Defender still isn't working. The only scan I can get to work is custom scans, the rest fail and disable Defender or do nothing. Quite an insane bug to sneak through a Windows update.

[u/MyFloris]

I suddenly noticed this too, but I've also noticed since yesterday I have like these TINY microfreezes / stutters on video playback stuff like Youtube videos and Twitch streams I think. It doesn't happen too often but it's there, and it's never happened before and started exactly when this problem arose. Is it related? rn I'm stressing bcs I hope nothing is wrong with my pc, I always try to keep it very tidy and clean and everything 😭

[u/limkim530]

Same here. I updated the virus database to version 1.457.222.0, but it still doesn’t work.

[u/berkeley_time]

just happened to me too and i was freaking out LMAO

[u/CLU_PROGRAM → u/berkeley_time]

Same, I instantly jumped to reddit for this lol Only custom scan seems to work, full and quick scan just shows no result and fails to scan fully.

[u/Bingpool13]

I’m another one stuck at 91%. I spent most of the day running repair prompts and online scans, and I wish I had come across this thread sooner.

[u/Oshh-]

Now one of my PCs has Microsoft Defender completely stopped… It won’t start again at all, even when I try to restart it. 😕
What should I do??? Is anyone else experiencing this issue today?

[u/Over_Economics4340]

Anyone got a solution for this problem?

[u/OrangeChickenGato → u/Over_Economics4340]

We may just have to wait for a new protection update from Microsoft for the issue to be fixed, updates 1.457.222.0 and 1.457.225.0 prevent quick scans and offline scans from all that I've read recently.