iMac Logs Out When Using Firefox 50.1.0

[CheMillan]

When I'm using Firefox 50.1.0 to check my Gmail, Firefox freezes for a few seconds then my iMac logs out and the login screen appears to enter my Mac's password. This problem started happening recently about 2 weeks ago every time I use Firefox to check my Gmail and only happens when I use Firefox. This is what I get from Console:

"12/20/16 11:33:29.845 AM firefox[212]: WARNING: The Gestalt selector gestaltSystemVersion is returning 10.9.5 instead of 10.10.5. Use NSProcessInfo's operatingSystemVersion property to get correct system version number"

I thought about downgrading to a previous version of Firefox to fix this. Any ideas, suggestions? Thanks.

My iMac Specs:
27" iMac Late 2013, iMac14,2
OS 10.10.5 Yosemite
8GB installed RAM
Wired keyboard
Wired Wacom Touch Tablet

 

[maflynn]

suggestions?

Don't use Firefox. I'm not trying to sound coy, if the app is causing issues, then find an alternative.

 

[briloronmacrumo]

When I'm using Firefox 50.1.0 to check my Gmail, Firefox freezes for a few seconds then my iMac logs out and the login screen appears to enter my Mac's password.

Definitely abnormal behavior. I'm using the same Firefox version on a 2011 iMac with no problems on El Capitan( 10.11.6 ). You might want to check a list of diagnostic steps ( #5 ) here

"12/20/16 11:33:29.845 AM firefox[212]: WARNING: The Gestalt selector gestaltSystemVersion is returning 10.9.5 instead of 10.10.5. Use NSProcessInfo's operatingSystemVersion property to get correct system version number"

That message has been around for years now. Going back to an older Firefox release won't eliminate it but it's doubtful the problem it describes is causing your issue.

I thought about downgrading to a previous version of Firefox to fix this.

I wouldn't bother. It's likely either a cache issue ( see Onyx tool ) or some Firefox preference file was damaged. You might have do to a reset Firefox to put all its settings back to standard ( and that's a guess - you need information first before making changes. See the diagnostic post mentioned earlier and the tools )

 

[CheMillan]

When I'm using Firefox 50.1.0 to check my Gmail, Firefox freezes for a few seconds then my iMac logs out and the login screen appears to enter my Mac's password. This problem started happening recently about 2 weeks ago every time I use Firefox to check my Gmail and only happens when I use Firefox. This is what I get from Console:

"12/20/16 11:33:29.845 AM firefox[212]: WARNING: The Gestalt selector gestaltSystemVersion is returning 10.9.5 instead of 10.10.5. Use NSProcessInfo's operatingSystemVersion property to get correct system version number"

I thought about downgrading to a previous version of Firefox to fix this. Any ideas, suggestions? Thanks.

My iMac Specs:
27" iMac Late 2013, iMac14,2
OS 10.10.5 Yosemite
8GB installed RAM
Wired keyboard
Wired Wacom Touch Tablet[/QUOTE

[doublepost=1482863020][/doublepost]

Definitely abnormal behavior. I'm using the same Firefox version on a 2011 iMac with no problems on El Capitan( 10.11.6 ). You might want to check a list of diagnostic steps ( #5 ) here

That message has been around for years now. Going back to an older Firefox release won't eliminate it but it's doubtful the problem it describes is causing your issue.
I wouldn't bother. It's likely either a cache issue ( see Onyx tool ) or some Firefox preference file was damaged. You might have do to a reset Firefox to put all its settings back to standard ( and that's a guess - you need information first before making changes. See the diagnostic post mentioned earlier and the tools )

I found the reason why Firefox 50.1.0 has been crashing and login out my iMac. I opened EasyFind and searched for Facebook Video and sure enough, EasyFind found a Facebook Video.app plugin inside the System Library folder. I clicked on Reveal in Finder using EasyFind, with the Finder window opened I clicked delete, enter the iMac's password to authenticate then emptied the Trash. Firefox 50.1.0 has stopped crashing and login my iMac out. So far so good.

 

[briloronmacrumo]

EasyFind found a Facebook Video.app plugin inside the System Library folder.

Yikes! Glad you found it. EasyFind is certainly a valuable tool for me too( I like 'Find Any File' too ). EtreCheck is my first stop for unusual app behavior.

If you know, the Mac community would probably appreciate knowing if that plugin was installed with your permission or without it. Typically, System/Library and much of its contents is protected unless the user authenticates a request for access.

 

[CheMillan]

I'm not sure if this was a malicious install without my permission but the instructions that I read online to fix the Firefox crashing problem was for Windows so out of curiosity I decided to search my iMac and try this fix and to my surprise it worked.