One of the extensions I have (gmail notificater) seemed to have caused the problem. Once disabled, the message disappeared. I would try disabling extensions and turning them on one by one to see who the culprit is.

As I wrote "Trying to disable all extensions and restating OSX. No help. "

I have the same issue - no virus software, no add-ons, mac os x 10.8.5 - upgrading from 29 to 29.01

Previous question said it was the extension Delicious Bookmarks 2.3.4, however it looks like in the past it was also caused by antivirus software.

• Does this happen in Safe Mode? Diagnose Firefox issues using Troubleshoot Mode
• Does this happen in a new profile when upgrading from 29 to 29.0.?

Please post back with results :-)

Yes, both in Safe Mode and with new profile it's working correctly.

Seems like the issue is related to add-ons, however once again I disabled all of them and the problem is still occuring (see screenshot).

Here is a silly question, is the offline installer window still open?

There is a hack called MOZ_NO_REMOTE that requires more than one instance of firefox: http://forums.mozillazine.org/viewtopic.php?f=38&t=429889

However this would imply that more than one profile is being used. In your Force quit menu is there more than one Firefox running?

Do not use the MOZ_NO_REMOTE environment variable, but use the -no-remote command line switch instead.

• https://developer.mozilla.org/Command_Line_Options

• http://kb.mozillazine.org/Opening_a_new_instance_of_Firefox_with_another_profile
• https://developer.mozilla.org/Mozilla/Multiple_Firefox_Profiles

Nope, no installer open. I have never used MOZ_NO_REMOTE.

However just checked the list of processes:

2844 8.8 4.5 3648204 755528  ?? R 9:18AM 4:36.59 /Applications/Firefox.app/Contents/MacOS/firefox

2846 0.0 0.1 2642356 23984  ?? S 9:18AM 0:00.16 /Applications/Firefox.app/Contents/MacOS/plugin-container.app/Contents/MacOS/plugin-container /Library/Internet Plug-Ins/Flash Player.plugin -greomni /Applications/Firefox.app/Contents/MacOS/omni.ja -appomni /Applications/Firefox.app/Contents/MacOS/browser/omni.ja -appdir /Applications/Firefox.app/Contents/MacOS/browser 2844 gecko-crash-server-pipe.2844 org.mozilla.machname.614707479 plugin

http://dpaste.com/0E4S5P3/

Maybe this might be helpful

bartek! http://security.stackexchange.com/que.../firefox-flash-plugin-malware Thank you for that, I found that omni.js is an alternative to info.zip? That may be spelled incorrectly, but this is a feature that some web developers maybe used incorrectly. Please install NoScript.

Not sure how this should help. Anyway, I installed and enabled the NoScript addon and don't see any difference. I still get this message about another instance.

Updated to 31.0 yesterday on OSX 10.9.4. Getting the message that "Firefox is being updated by another instance" from the About menu.

FF Safe Mode doesn't help, and I have no extensions installed. Rebooting OSX doesn't help either. It seems mostly cosmetic at this point but still annoying.

I restarted and the notice is gone.

Chupacabraz try to reinstall your flash plugin it looks like the logs provided by bartek shows the last line as the plugin crashing in gecko. Does a new profile help? If not let's start a new question with your troubleshooting info.

I have the same issue here but it only happen when using the default profile in firefox, meaning that if I use "safe profile" or the one that I call "surf" (lacking gmail addon and some others) I get the normal message. It seems strange to me that this issue (described for the first time at least 6 mm ago) is still open. Not a big deal (I upgrade manually or just using other profiles) if this is not a security issue. Am I wrong?

ff 33 OSX 10.6.8