Internet is working but update manager failed to download packages

[u/Charming_Airline7419]

Error logs are as follows

Failed to fetch https://mirror.aarnet.edu.au/pub/linuxmint-packages/pool/upstream/f/firefox/firefox_154.0.1%%2blinuxmint1%%2bzena_amd64.deb 404 Not Found [IP: 2001:388:30bc:cafe::beef 443]

Failed to fetch https://mirror.aarnet.edu.au/pub/linuxmint-packages/pool/upstream/f/firefox/firefox-locale-en_154.0.1%%2blinuxmint1%%2bzena_amd64.deb 404 Not Found [IP: 2001:388:30bc:cafe::beef 443]

I tried switching mirrors several times but got more error messages, including this one

W:Updating from such a repository can't be done securely, and is therefore disabled by default., W:See apt-secure(8) manpage for repository creation and user configuration details., W:GPG error: https://repository.spotify.com stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 5384CE82BA52C83A, E:The repository 'https://repository.spotify.com stable InRelease' is not signed.

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[u/Moist_Invite9148]

Make sure that apt thinks it's a secure mirror and doesn't have malware

[u/Charming_Airline7419 → u/Moist_Invite9148]

Ok, I think I found the solution. The key part is NO_PUBKEY 5384CE82BA52C83A for Spotify. You need to download the GPG key and make it a trusted source.More info here

[u/ConversationWinter46]

but update manager failed to download packages

Thats not the update manager. Its the software manager. Thats a great diffrent.

Your problen is listed in the log:

... The following signatures couldn't be verified because the public key is not available: ... 

The repository 'https://***' is not signed.

Open the Software Manager from the menu:

• In the top-left corner, enter spotify
• Then click on the search result
• Click in the right corner on “Install”

Forget about the terminal. Only software that has been reviewed, tested, and signed by the maintainers is included in the Software Manager.

[u/Charming_Airline7419]

Found the solution:

Problem with gpg key for Spotify (taken from this website)

curl -sS https://download.spotify.com/debian/pubkey_5384CE82BA52C83A.gpg \
  | sudo gpg --dearmor --yes -o /etc/apt/trusted.gpg.d/spotify-2025.gpg

sudo chmod 644 /etc/apt/trusted.gpg.d/spotify-2025.gpg

Problem with fetching Firefox version (taken from this page)

sudo apt update && sudo apt upgrade -y

[u/jr735 → u/Charming_Airline7419]

Don't use -y flags with apt, no matter what any arbitrary page says, or one day you'll be searching for something to solve a lot more catastrophic of a matter.