Users who upgraded to the Ubuntu 25.10 release, faced with the inability to install or update Flatpak packages. The problem is caused by changes in the AppArmor rules applied when running the fusermount3 utility. Due to incorrectly set access rules, attempts to install or update packages using the flatpak utility result in an error message stating that it is impossible to unmount the /var/tmp/flatpak-cache-* directory.
The issue has been assigned a critical severity level. Currently, an update to the package with AppArrmor rules has been prepared and is being tested, until it is ready as a workaround for a temporary solution to the problem disable Apparmor profile for fusermount3.
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