Fixing Firefox APT Repository Error

Fixing Firefox APT Repository Error | Generated by AI

Home 2025.10

The error you’re seeing is specific to the Mozilla Firefox APT repository (https://packages.mozilla.org/apt), where the fetch for the binary-all/Packages index file fails with a 400 Bad Request. This is a known intermittent issue reported by other Ubuntu/Debian users, often tied to proxy configurations (your local proxy at 127.0.0.1:7890 suggests something like Clash, V2Ray, or a similar tool is in play, which can mangle HTTPS requests for APT). The good news is that APT ignores the failure and uses cached/old indexes, so system updates aren’t blocked—but it can prevent getting the latest Firefox deb packages.

Quick Fixes to Try (in order)

Clear APT cache (this resolves corrupted or stale index files, which fixed it for several users):
```
sudo apt clean
sudo apt update
```
Temporarily bypass your proxy for APT (since the 400 often stems from proxy interference with the repo’s HTTPS):
```
unset http_proxy https_proxy all_proxy
sudo -E apt update
```
- Run this in the same terminal session. If it works, you can make it permanent by adding the unset lines to your ~/.bashrc (or just before APT commands) or disabling the proxy app briefly.
- If your proxy is set system-wide (e.g., in /etc/environment), edit that file to exclude APT or comment out the lines temporarily.
Disable proxy globally for APT (if the above works but you want a set-it-and-forget-it option):
```
echo 'Acquire::http::Proxy "";
Acquire::https::Proxy "";' | sudo tee /etc/apt/apt.conf.d/99no-proxy
sudo apt update
```
- This tells APT to ignore proxies entirely. Revert by deleting /etc/apt/apt.conf.d/99no-proxy if needed.

If You Need Latest Firefox Without the Repo

If the repo keeps failing and you just want updated Firefox:

Switch to Snap (Ubuntu’s default, easy updates, no repo hassle):
```
sudo snap install firefox
```

Or Flatpak (if you prefer):

sudo apt install flatpak
flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
flatpak install flathub org.mozilla.firefox

Prevention/Notes

The Mozilla repo is unofficial for getting bleeding-edge Firefox debs—consider sticking with Ubuntu’s snap version unless you specifically need the deb.
If none of this works, check your proxy logs (e.g., Clash dashboard) for rejected requests to packages.mozilla.org, or test without the proxy entirely.
Run sudo apt update again after fixes to verify.

If these don’t resolve it, share more details like your proxy setup or full /etc/apt/sources.list.d/mozilla.list contents for deeper troubleshooting.

Ubuntu 23.10 - Update Problems
Firefox apt repository error

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