AppImage: "error loading libfuse.so.2" on recent Ubuntu

linux - 2026-11-01

I hadn't used a graphical Linux desktop since Mandrake, a Linux distribution from the late 1990s and early 2000s later renamed Mandriva. Linux has been terminals and servers for me since. So installing one graphical tool meant learning a few things that are probably obvious to people who never left the Linux desktop, starting with AppImages and FUSE.

An AppImage is a Linux application packed into one executable file, with no installer and no package manager. Many desktop tools ship that way, including Headlamp, a graphical interface for Kubernetes clusters (Kubernetes itself is explained in what Kubernetes is). The example here is Headlamp 0.46.0 on Ubuntu 26.04, run under WSL2, though nothing in this entry depends on WSL.

Homebrew installs the AppImage but no command

Homebrew is a package manager from macOS that also runs on Linux. Its casks are packages for graphical applications. brew install headlamp downloads the AppImage, then:

==> Moving App Image 'Headlamp-0.46.0-linux-x64.AppImage' to '/home/abdel/Applications/Headlamp.AppImage'
🍺  headlamp was successfully installed!

and headlamp then answers command not found. The cask definition has only an app_image line on Linux, which moves the file to ~/Applications. Nothing is linked into a directory on PATH, so add the link yourself:

mkdir -p ~/.local/bin
ln -sf ~/Applications/Headlamp.AppImage ~/.local/bin/headlamp

Ubuntu's default ~/.profile adds ~/.local/bin to PATH when the directory exists at login.

The error

dlopen(): error loading libfuse.so.2

AppImages require FUSE to run.
You might still be able to extract the contents of this AppImage
if you run it with the --appimage-extract option.

FUSE (Filesystem in Userspace) lets an ordinary program provide a filesystem. An AppImage uses it to mount its own contents and run the application from there. The application itself doesn't use FUSE; the runtime does, the small program at the start of the AppImage file that does the mounting. Recent Ubuntu releases ship FUSE 3 and no longer install version 2 by default, and which one matters depends on the runtime:

• The older runtime loads version 2 of the FUSE library, libfuse.so.2, when it starts. Version 3 (libfuse3.so.3) is a different library and doesn't help.
• The newer type2-runtime is linked statically, and its README says libfuse2 is then no longer required on the system.

Which runtime an AppImage carries

Look for the library name in the start of the file, without running it:

head -c 1000000 ~/Applications/Headlamp.AppImage | strings | grep -m3 -i 'libfuse'

Headlamp 0.46.0 prints the older runtime's strings:

libfuse.so.2
dlopen(): error loading libfuse.so.2
dlsym(): error loading symbol from libfuse.so.2

For that runtime, FUSE 2 has to be installed. It can sit side by side with FUSE 3.

Install FUSE 2 next to FUSE 3

Check whether the library is there. ldconfig -p prints the cache of shared libraries that the dynamic loader (the part of Linux that finds shared libraries when a program starts) knows about, which is what dlopen() searches:

ldconfig -p | grep libfuse

No libfuse.so.2 line means it's missing. Install it:

sudo apt install libfuse2t64     # Ubuntu 24.04 and later
sudo apt install libfuse2        # Ubuntu 22.04

Ubuntu 24.04 renamed libfuse2 to libfuse2t64, part of the switch to a 64-bit time_t (the type that holds timestamps). On 24.04 libfuse2 has no installable version any more, and libfuse2t64 declares that it provides and replaces it. Afterwards the check shows:

    libfuse.so.2 (libc6,x86-64) => /lib/x86_64-linux-gnu/libfuse.so.2

Don't install the package called fuse to get it. On 24.04, fuse3 declares that it breaks and replaces fuse, so installing fuse makes apt remove fuse3, which other packages may need. The library package alone is enough for an AppImage.

Without installing anything

The AppImage runtime can extract itself to a temporary directory, run from there, and clean up when the application exits. It's slower at every start:

~/Applications/Headlamp.AppImage --appimage-extract-and-run

If the AppImage then starts but no window opens under WSL2, with Missing X server or $DISPLAY, the cause is WSLg, not FUSE: see WSLg: "Missing X server or $DISPLAY".

Sources

• AppImage docs, I get some errors related to something called "FUSE" (FUSE 2 alongside FUSE 3, the libfuse2t64 rename, extract-and-run), from AppImage/docs.appimage.org, fetched 2026-11-01.
• AppImage/type2-runtime README: the statically linked runtime, fetched 2026-11-01.
• Homebrew's headlamp cask, version 0.46.0.
• The package facts (libfuse2t64 replacing libfuse2, fuse3 breaking fuse, the ldconfig -p output) were checked with apt on Ubuntu 24.04 in the Linux cloud container where this entry was drafted. The Headlamp install, the runtime check and the error happened on Ubuntu 26.04.1 under WSL2; the AppImage itself didn't run in the container.

Created 2026-11-01T17:25:06+01:00 · Edit