sorry - forgot to add: everything else in the tools drop down works. Addons fails

It is possible that there is a problem with the file(s) that store the extensions registry.

Delete the files extensions.* (e.g. extensions.sqlite, extensions.ini, extensions.cache) and compatibility.ini in the Firefox profile folder to reset the extensions registry.

• https://support.mozilla.org/kb/Profiles

New files will be created when required.

See "Corrupt extension files":

• http://kb.mozillazine.org/Unable_to_install_themes_or_extensions
• https://support.mozilla.org/kb/Unable+to+install+add-ons

If you see disabled, not compatible, extensions in "Tools > Add-ons > Extensions" then click the Tools button at the left side of the Search Bar (or click the "Find Updates" button in older Firefox versions) to check if there is a compatibility update available.

If this hasn't helped then also try to delete the addons.sqlite file.

Hi Cor-el TY for your response. I started FF in safe mode, [selected help/restart with addons disabled] then I could see the addon list. Then I restarted FF and the problem is fixed. How odd. At least it is working now.

Now I see that todays special probleme swith the new FF include: under "Help" ALL these are not active: FF help + troubleshooting + submit feedback. I am getting >>>OFF<<< this beta update channel. what is WRONG with FF. Corel, thanks for your answers, but i am not a programmer ,and your instructions were very hard to follow, maybe someone with a degree in computer science coudl follow them. thanks anyway

Followed your instructions. Through trial and error, found that Tab Mix Plus 0.4.0.3 causing problem. Disabled and everything now works. Will wait for update from them. Thanks Cor-el.

Thx Electra - I removed tab mix plus and the FF help + troubleshooting + submit feedback work again. Will not ever use tab mix plus after this. If an addon screws up FF, i do not use it again.

Tab Mix Plus has a beta update (0.4.0.4) available that fixed the problem. I have TM+ enabled again.