Preferences not saved
You may not be able to save any preference settings and you may receive an error similar to "Failed to save the preferences file. Any preference changes will be lost at the end of the session" [1]. You may also find multiple files named "prefs-n.js" (where n is a number) appearing in the profile folder.
This problem can be caused by having the prefs.js or "prefs.js.moztmp" file in the profile folder set to read-only or hidden. Remove the "read-only" attribute to resolve the issue.
Note that other read-only files in the profile folder can cause similar problems, for example, a read-only cookies.txt or "cookies.txt.moztmp" file can cause loss of cookie data and creation of multiple cookies files and a read-only bookmarks.html or bookmarks.html.moztmp file can cause bookmarks not to be saved and creation of multiple bookmarks files.
Related bugs
- Bug 157152 - read-only/hidden bookmarks.html (or bookmarks.html.moztmp) causes creation of bookmarks-{n+1}.html
- Bug 257288 - read-only profile files (cookies, bookmarks, etc) not respected, results in data loss
