User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0 Build ID: 20160315153207 Steps to reproduce: Run Firefox. (System also runs Kaspersky Internet Security with default settings, which may trigger problems in Firefox) Actual results: Once in a while, after several months of daily Firefox usage, Firefox silently creates a new profile by itself without telling the user. Firefox starts with that new profile as default without having imported anything. In the root profile folder there are suddenly two non empty profile folders instead of one containing the string "default", but when starting with the profile manager only one profile is shown. It seems the other one is corrupt but nothing is reported to the user. An inexperienced user could assume Firefox deleted all data and settings and resetted everything. Expected results: Firefox shall never create profiles by itself without notifying the user. If there is something wrong, report it to the user! Show an error log so the user can trace the problem. Unspecific error messages like "cannot load profile" or just "Error" are mostly useless. If a file in the profile appears to be invalid, tell the user which file.
Component: Untriaged → Startup and Profile System
Product: Firefox → Toolkit
The only thing I can come up for with this behavior is if profiles.ini is missing/corrupt, in which case we start over as if Firefox is brand-new on the system. I think we should add telemetry for various cases here, to see how much this shows up in the wild!
Priority: -- → P3
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