Getting the same after the update, the first time i try open firefox it will be just a blank page, opening TaskManager can see there would be 3 processes running for firefox one of those would be show in red as Not Responding, ending task and reopening firefox then run fine,

the problem will be back again then next time you close and try open firefox.

im seeing a few report of this bug on reddit and here on help forum tho no fix yet other then the nuclear option of a new profile.

it's a weird one tho as when you get it running it work fine as long as you dont close it, the bug is only in the first launch.

After the latest update, it takes two tries to open Firefox. The first time I get a blank page, which I close (and it's supposedly reported to Microsoft.) The second time I open it, I get a message about starting a new session, which I click, and then it opens properly. This has happened every time since the latest update.

It sounds like the second start is a crash recovery, so something is causing a crash or freeze on the first try but not on the second. It's difficult to think of what that might be off the top of my head. I suspect it is a different problem that the one joelol mentioned that is discussed further in the following thread: https://support.mozilla.org/questions/1407995 (unsolved).

Does the problem only occur after system startup, or does it happen every time you exit Firefox and restart it (fails, recovers, fails, recovers)?