FUSE

AppImages require FUSE to run. Filesystem in Userspace (FUSE) is a system that lets non-root users mount filesystems.

Install FUSE

Many distributions have a working FUSE setup out-of-the-box. However if it is not working for you, you may need to install and configure FUSE manually.

For example, on Ubuntu:

sudo apt-get install fuse
sudo modprobe fuse
user="$(whoami)"
sudo usermod -a -G fuse $user

For example, on openSUSE:

sudo zypper install fuse

As of May 2017, it is necessary on the Tumbleweed (at least on the Live ISO) to also run

chmod a+x /usr/bin/fusermount
chown root /usr/bin/fusermount
chmod u+s /usr/bin/fusermount

Quite possibly this is a Tumbleweed bug.

For example, on CentOS/RHEL:

yum --enablerepo=epel -y install fuse-sshfs # install from EPEL
user="$(whoami)"
usermod -a -G fuse "$user" 

For example, on Armbian 64-bit systems (e.g., for the Pine64) you need to install 32-bit libfuse2 in order to run 32-bit AppImages such as the MuseScore one:

sudo apt install libfuse2:armhf

Fallback

If you don't want to install FUSE, you can either mount or extract the AppImage.

To mount the AppImage and run the application, simply run

sudo mount -o loop Some.AppImage /mnt
/mnt/AppRun

If that does not work, you might have an experimental type 2 AppImage. These can directly be extracted. Run the AppImage with --appimage-extract to extract the contents of the AppImage.

Docker

When running an AppImage from a Docker container you will get the following error:

fuse: failed to open /dev/fuse: Operation not permitted
Could not mount AppImage
Please see https://github.com/probonopd/AppImageKit/wiki/FUSE

unless you add these arguments to docker run: --cap-add SYS_ADMIN --cap-add MKNOD --device=/dev/fuse

If you're running an Ubuntu container you may need this one as well: --security-opt apparmor:unconfined