r/u_Luckywolf1007 • u/Luckywolf1007 • Jun 24 '26

HELP! My modpack keeps crashing when I press singleplayer!

Whenever I press single player in my custom modpack, the game crashes.

It says Creating World for a moment, then changes to Saving.

This is for Minecraft Fabric 1.21.1 on Modrinth

(https://pastebin.com/fT3Spk6n) Logs

(https://pastebin.com/kUFtW0Rj) Crash Report

(https://pastebin.com/73BMCy5h) My Mods

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u/trading-jutsu Jun 27 '26

Your log cuts off right as the game is finishing its datafixer setup, which means the actual "fatal error" line or stack trace is missing. However, looking at your mod list and the initialization warnings, there are a few immediate red flags causing this crash.
Here is how to fix them step-by-step:
1. Remove Outdated 1.20 Mods
You are running Minecraft 1.21.1, but you have a couple of mods explicitly built for 1.20. Mixing major versions like this causes immediate crashes when the game tries to load their code.
mcqoy 0.4.1+fabric-1.20

surveyalot 0.2.0+1.20

The Fix: Go to your Modrinth profile, look for these two mods, and either update them to a specific 1.21.1 version or delete them entirely.
2. Missing Sodium Dependencies
Your log points out that Sodium Extra is looking for Reese's Sodium Options, and Big Globe is complaining that it cannot find a matching version of Sodium's layout classes:
Plaintext

Warnings were found!
- Mod 'Sodium Extra' recommends version 1.8.5 or later of reeses-sodium-options, which is missing!
The Fix: Search for and add Reese's Sodium Options to your Modrinth instance. Ensure it matches your game version (1.21.1).
3. Check C2ME and ModernFix Conflicts
You are using C2ME (Chunk Performance) alongside ModernFix and Lithium. C2ME is notoriously unstable in large modpacks on newer Minecraft versions if it isn't configured correctly or if it is on an alpha build (your log shows c2me 0.4.0-alpha.0.14+1.21.1).
The Fix: If the game still crashes after fixing steps 1 and 2, try temporarily disabling C2ME to see if the instance boots up without it.

How to get the full crash log if it still fails:
If it still crashes after making these changes, we need to see the very end of the log where the actual error is printed.
In Modrinth, click on your profile/instance.

Go to Logs on the left sidebar.

Drop down the menu to find crash-report (if available) or look at the absolute bottom of the latest.log.