I have installed the Beta version and to my surprise flatpak apps does not install. Yes I have taken all the pre installation from the flathub page. I get this error when I try to install a flatpak app:
{system/flatpak/flathub/org.freedesktop.Platform/21.08} Kunne ikke afmontere filsystemet revokefs-fuse på /var/tmp/flatpak-cache-TYBJD3/org.freedesktop.Platform-N2WGD3: Underproces afsluttede med kode 1
These are the steps I took so far:
sudo apt update
sudo apt install flatpak -y
sudo flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
sudo apt install gnome-software-plugin-flatpak -y
Log out and in again or reboot for integration to take effect.
What specific flatpak did you try installing?
First, thx 4 ur reply. I took all the prelimininary steps on the flathub homepage “how to setup stuff” for Ubuntu. It usually works flawlesly, but in Ubuntu 25.10 beta, not so much. I tried to install libreoffice, onlyoffice, gimp, audacious, Rhythmbox all my usual aps and the same error msg shows for all. I usually copy paste from flathub to terminal. This time I did both use the Software and Flathub with same outcome. Are you on the 25.10 Beta too?
I set up a VM with 25.10 Beta to test this and see if I can reproduce the errors.
I will try some of those apps and report back.
Thanks again. I tried this morning to install flatpak apps in the new Software store with same error msg. I think maybe it’s because it’s a beta and not fully integrated yet.
I get the same errors whether trying to install from the terminal or Gnome Software.
More than likely related to this bug:
You can add yourself as being affected and leave a comment that you are on the beta version.
One user suggested a workaround but I have not tested it.
Since the software sources are for 25.10 it is not possible to downgrade the version of fuse3.
However, if you are feeling adventurous you can download and install the .debs manually.
https://archive.ubuntu.com/ubuntu/pool/main/f/fuse3/fuse3_3.14.0-10_amd64.deb
https://archive.ubuntu.com/ubuntu/pool/main/f/fuse3/libfuse3-3_3.14.0-10_amd64.deb
Then like this in the terminal:
cd Downloads
sudo dpkg -i fuse3_3.14.0-10_amd64.deb
sudo dpkg -i libfuse3-3_3.14.0-10_amd64.deb
If there are any missing dependencies (which there will be):
sudo apt --fix-broken install
Hold the packages to prevent automatic upgrades:
sudo apt-mark hold fuse3 libfuse3-3
Reboot and try installing the flatpaks again.
As a test I installed Gimp in the terminal. It installed without errors and I opened it to check, no issues.
Personally, I do not recommend downgrading and holding packages like this unless strictly for testing purposes.
Therefore, if you decide to try this it is entirely at your own risk.
Thank you for your effort here. I think I’ll pass and wait to see if it has been fixes when the final version is realeased. Thanks again.
There is another solution to this problem.
If this application installs and runs on Ubuntu 25.04 or Ubuntu 24.04 LTS, then stay on that version of Ubuntu until the application developer upgrades the application to install on the newer versions of Ubuntu.
Will this application install as a Debian packaged version? I do not think so. This is a recurring problem - application developers not keeping their applications up to date with developments in the operating system. It has been going on for decades with Debian packaged applications.
By the way, if I understand things correctly, Snap packages are supposed to contain all the dependencies in the snap package. I have snaps of core18; core22; and core24. If an application needs a dependency from Ubuntu 18.04; 22.04 or 24.04 then it will find that dependency in those snap packages. Provided, of course, that the application developer has made sure that the application looks for the right core snap package.
I do not see the problems of Flatpak applications not keeping up with Ubuntu developments as a problem for Ubuntu developers to fix.
P.S. I quote from Flatpak.org
Flatpak makes it easy to bundle your own libraries as part of your app.
A temporary workaround is to disable the Apparmor profile for fusermount3:
sudo ln -s /etc/apparmor.d/fusermount3 /etc/apparmor.d/disable/
sudo apparmor_parser -R /etc/apparmor.d/fusermount3
To later re-enable the profile (once the bug is fixed):
sudo rm /etc/apparmor.d/disable/fusermount3
cat /etc/apparmor.d/fusermount3 | sudo apparmor_parser -a
See also Bug#2122161
I appreciate your input. It makes good sense. I was impatient because I am used to using flatpaks rather than snaps. I’ll just lean back and wait for the final version to be released. Thanks again.
Thank you for sharing the fix! Works perfectly.
You are most welcome.
Here’s another fix:
I used the steps described here
I can confirm it works; I’m now able to install Flatpaks in Ubuntu 25.10.
I suggest backing up the file before you edit, just in case you want to restore it.
Considering the disparity in what apps are available for Snap vs Flatpak, I sure hope this gets fixed fully before the release date so those of us who default to Flatpak for its rich app offerings can use that and not have to depend on Snaps, which are oft outdated and with a much more limited app offering.
Moderator Note:
We will NOT be entertaining Flatpak vs Snap opinions in this topic.
We will NOT tolerate denigrating either packaging system.
The topic of this discussion is factual discussion of a specific bug.
Please stay on topic.
Hello, your solution worked. I would like to know how I can find out when the bug is fixed so that I can reverse it and enable it again.
The same problem persists today, October 9.
Thank you.
The bug is linked in jan-r’s post … just check it regularly or subscribe to it to get updates by mail …
reparar flatpak ubuntu 25.10
Edit /etc/apparmor.d/fusermount3 in your favourite text editor, via sudo
Add at line 11 (which should be empty) add: /run/mount/utab.lock rwk,
Save & exit
Reload the fusermount3 rules: sudo apparmor_parser -r /etc/apparmor.d/fusermount3
Try again.