After a recent system update on Arch Linux, video playback in LibreWolf suddenly stopped working.
At first, it wasn't obvious what had changed. I went through the usual possibilities, including hardware acceleration, VPN/DNS issues, browser cache, and other playback-related settings.
Eventually, the timing pointed toward an FFmpeg update.
The Problem
LibreWolf was no longer able to play videos correctly after the system update.
The browser reported:
NS_ERROR_DOM_MEDIA_METADATA_ERR
The important part was that normal browsing still worked. The failure was specific to media playback.
That left several possible places to investigate.
What I Tried
I started with the usual browser-side checks.
I checked hardware acceleration and browser-related settings to make sure the problem wasn't caused by a configuration change inside LibreWolf.
I also looked at the VPN and DNS configuration because the problem initially happened while the VPN was being used.
The OpenVPN logs showed:
Initialization Sequence Completed
So the VPN connection itself was completing successfully.
There was also a resolvconf warning:
resolvconf: signature mismatch: /etc/resolv.conf
I checked the resolver state and manually ran:
sudo resolvconf -u
That completed without producing the previous lock error, but it did not fix LibreWolf's media playback.
At that point, the network configuration was looking less likely to be the cause.
What I Found
The investigation eventually moved toward the multimedia libraries used by LibreWolf.
The important change in the system update was an FFmpeg major-version update from 8 to 9.
That timing stood out because FFmpeg major releases can involve changes to the libraries applications depend on. If an application or package hasn't been updated for the new library interface yet, compatibility problems can occur.
That matched what I was seeing.
The problem was no longer looking like a VPN, DNS, browser-cache, or ordinary browser-settings issue.
The FFmpeg update provided a much stronger lead.
The Compatibility Problem
The evidence pointed toward a compatibility problem between the updated FFmpeg libraries and the LibreWolf build installed on my system.
The important distinction is that this does not mean that FFmpeg 9 itself was broken.
The problem was the transition between major library versions and whether the application using those libraries was ready for that change.
In my case, the installed LibreWolf package had not yet caught up with the transition.
The Workaround
I tested the compatibility theory by installing the older FFmpeg compatibility package:
sudo pacman -S ffmpeg4.4
The ffmpeg4.4 package provides the older FFmpeg 4.4 libraries alongside the current FFmpeg package.
After installing it, LibreWolf was able to play videos again.
That gave me a much stronger connection between the FFmpeg transition and the playback failure.
Verification
The verification was simple.
I opened the same video that had previously failed.
After installing ffmpeg4.4, playback worked again.
That made the compatibility explanation much more convincing than the earlier theories around VPN, DNS, hardware acceleration, or browser cache.
The important sequence was:
FFmpeg update
↓
LibreWolf media playback fails
↓
ffmpeg4.4 installed
↓
Media playback works again
This was also consistent with a recent Arch Linux forum report from August 2026 where LibreWolf video playback broke after the FFmpeg 8 → 9 update and ffmpeg4.4 was used as a temporary workaround until a LibreWolf update resolved the issue.
Trade-offs
ffmpeg4.4 is a workaround, not necessarily the permanent solution.
The better long-term solution is for the affected application/package to support the newer FFmpeg libraries.
That means the compatibility package may no longer be necessary once LibreWolf and its dependencies have caught up with the newer FFmpeg version.
I would therefore treat the older package as a temporary compatibility measure rather than something that should automatically be kept forever.
What I Learned
A major multimedia-library update can break an application even when the application itself appears to be working normally.
The useful clue here was the timing.
Video playback stopped working immediately after a significant system-library update, while the rest of the browser continued working.
That made the changed multimedia libraries worth investigating.
The troubleshooting path ended up looking like this:
Media playback failure
↓
Browser settings checked
↓
VPN/DNS checked
↓
Network issue became less likely
↓
FFmpeg major update noticed
↓
Compatibility tested
↓
ffmpeg4.4 restored playback
The error initially looked like a browser media problem.
The actual investigation led underneath the browser, into the system multimedia libraries it depended on.
If You Hit Something Similar
If LibreWolf or another application suddenly stops playing media after an Arch Linux update, check:
- The exact media error
- Recent package upgrades
- FFmpeg version changes
- Browser and multimedia-library dependencies
- Hardware-acceleration settings
- Whether the problem occurs with different media sources
- Whether a newer application build is available
The package-update history can be especially useful when the failure starts immediately after a system upgrade.
Don't keep changing browser settings indefinitely if the problem started at exactly the same time as a major dependency update.
Check what changed underneath the application.
Environment
The relevant environment during testing was:
OS: CachyOS
Browser: LibreWolf
Session: Wayland
Desktop: KDE Plasma 6
FFmpeg: 8 → 9 transition
Compatibility package tested: ffmpeg4.4
Your exact behavior may differ depending on your LibreWolf version, FFmpeg version, package source, and system configuration.
Final Takeaway
The problem initially looked like a LibreWolf media error.
The timing of the failure pointed toward the FFmpeg 8 → 9 transition.
Installing ffmpeg4.4 restored video playback on my system, which provided a practical compatibility workaround.
I would treat that as a temporary measure rather than a permanent fix. Once the affected LibreWolf package supports the newer FFmpeg libraries correctly, the compatibility package should no longer be necessary.
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