Are you using an antivirus? If so this may be preventing an update? Try stopping the antivirus and see if this message still appears.

I hope this helps.

Hi, yes I was but I uninstalled it and the problem still occurs.

Hi I found it. The issue was caused by the extension Delicious Bookmarks 2.3.4. With that disabled, all works fine,

cheers

I have this problem too. I'm have a Macmini running Snow Leopard 10.6.8. This has never happened before. I did notice though that my page is different now. So did it download or not? So what do I do?

I know I have Firefox 29, but how can I stop this message that another instance is updating? Should I leave it alone or download again it manually?

Hi, check your extensions. It's probably one of those making mess with Firefox and causing the issue. Disable all extensions, restart Firefox and see if it works fine then.

It was my Gmail Notifier. When I enabled it, it did the same thing so that was the culprit. Should I keep it disabled?

Hi hschaars, Please try another thread for your question if the issue continues. Gmail Notifier can be reinstalled, but if the issue is constant with a new reinstall, report it to the developer of the add on as well please :-)

I have the same problem on mac os x 10.8.5 and no virus software. I tried to disable all add ons but that didn't help. Upgrading from 29 to 29.1

lance000 if you would like separate help please start a new thread. Or if this is an issue with Delicious, please contact the add on developer as well. Thank you.