User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:58.0) Gecko/20100101 Firefox/58.0 Build ID: 20170926220106 Steps to reproduce: This is Nightly, but I have had this problem in this machine running other releases, for quite a while. Windows 7, Maintenance service is enabled, and McAfee is running. I click in help, about, reboot to update Actual results: Firefox reboots but the update state is still pending Expected results: It should have been updated.

The log (thanks for providing a log, by the way) shows that renaming firefox.exe failed. This tends to happen either because some other software has locked firefox.exe (most commonly this is some kind of security software) or because Firefox did not shut down properly and is still running when the updater tries to patch it. Your somewhat unusual installation location (it's different from our installer's default when installing into a user profile) makes me suspect the first option might be the issue; perhaps McAfee is surprised to see an executable running out of that location and is subjecting it to some extra scrutiny. Would you be able to try disabling McAfee or creating an exception for that directory (if that's possible, I'm not familiar with how it works anymore) and see if the problem persists? Thanks.

There is no other process locking the file, but McAfee injects the HIP DLL to the updater process, which I guess, blocks CreateFile/CreateFileMapping (I'm attaching a Process Monitor log file). HIP is enabled via GroupPolicy and can't be disabled. Updating via the installer works flawlessly (after UAC prompt).

The result from the CreateFile call is ERROR_SHARING_VIOLATION, so if you didn't find any handles held by other processes and no firefox.exe processes were still running, then yes, it seems like the injected McAfee DLL's (HcThe.dll and HcApi.dll) must be messing with us. This may need to be run by someone at McAfee.

Chris, would you be the one to ask about getting in contact with someone at McAfee? It looks like their Host Intrusion Prevention product might be getting in the way of our updater, at least when Firefox is installed to a custom location.

(In reply to Matt Howell [:mhowell] from comment #4) > Chris, would you be the one to ask about getting in contact with someone at > McAfee? It looks like their Host Intrusion Prevention product might be > getting in the way of our updater, at least when Firefox is installed to a > custom location. I CC'd you on an email to Adam Stevenson from our partner relations team.

It turns out there was already a Mozilla/McAfee discussion mailing list; I've just sent a message there regarding this bug.