User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0 Build ID: 20170928210252 Steps to reproduce: Dear Sirs, I do not know that is this a bug or feature, but on a Linux at least it is possible to wipe out the main Firefox directory using the command line and the Profile Manager. The recipe: 1. It is possible to create a Profile without a name by issuing the following command: # firefox-esr --no-remote --CreateProfile "" This works as expected and creates a 'xxxxxxxx.' directory inside the default '~/.mozilla/firefox' folder. 2. But there is also an option to provide the Profile directory. It is possible to run this command: # firefox-esr --no-remote --CreateProfile '"" /absolute/path/.mozilla/firefox/' As a result the main Firefox directory is treated as a profile directory for the unnamed Profile. prefs.js appears inside the ~/.mozilla/firefox/. 3. Now, using the Profile Manager we can delete the unnamed profile with its files (it appears as a user icon without a name). The actual problem is here: because the main Firefox directory is treated as the profile directory, it will be deleted, with all its contents --- profile folders of other Profiles, etc. Actual results: The main Firefox directory (~/.mozilla/firefox/) is no more. Expected results: I think that the Firefox shouldn't allow for empty Profile names and using its own main directory as a storage for a Profile.