Environment:
Win 11 non-administtrator account
Portable apps directory located on Desktop under user directory
Steps to reproduce:
1. Download and install Firefox Portable (Including beta and nightly) from portableapps.com's app launcher's "Portable App Directory"
2. Run it
3. Go to help, check for update, download and install
4. Restart Firefox
Expected behavior
Firefox starting normally (Same as in Win 10 etc)
Actual behavior
It would not launch, process name would appear in task manager for a few seconds, but then disappear
Note
1. It wouldn't be possible to uninstall/delete the unlaunchable Firefox instance either, with everythings under /FirefoxPortable/Data/profile/ being requiring administratior permission to delete, unless first moved to other locations
2. It would happen even when Firefox is at other location and even without updating, although not immediately
Do you have Firefox installed locally and did the enable update service in about:config somehow get set to true within Firefox Portable?
UPDATE: I can't reproduce this on Windows 11 64-bit even with Firefox installed and changing the portable version's about:config setting to use the service.
Sometimes, the impossible can become possible, if you're awesome!
No local firefox installation
I didn't check auto update service, but I went to Menu > Help > About Firefox > Update
Edit: Also, looking at about:profiles, despite being installed via portableapps launcher, all firefox profiles are using AppData\Roaming\ and AppData\Local\ for unknown reason