I have packaged and installed Slicer 4.13.0-2021-03-16 (from a local build) into a system location for all users at “C:/Program Files/Slicer 4.13.0-2021-03-16”, however I’m unable to install extensions.
The following message appears in the console output at startup.
"Failed to create extensions directory" "C:/Program Files/Slicer 4.13.0-2021-03-16/bin/../NA-MIC/Extensions-29780"
This message shows when opening the extensions manager.
The main reason for installing extensions in the application home folder is that Python packages are installed there anyway, so the application home folder has to be writable (or Slicer has to be run as admin when you install extensions). It also allows making Slicer fully portable - see details here.
If you want to allow any user to install extensions without admin rights and you only need to use extensions that don’t install Python packages at runtime then you can specify a custom extension install path folder in Slicer-NNN.ini file or revert to the old behavior of Slicer by specifying
Slicer_STORE_SETTINGS_IN_APPLICATION_HOME_DIR:BOOL=OFF when configuring your Slicer build.