Just to clarify:

Firefox 41 beta requires extensions to be signed by the Mozilla Add-ons review team. If you need to use unsigned extensions in Firefox 41, there is a preference you can change in about:config: xpinstall.signatures.required (change from true to false).

Firefox 40 does not require extensions to be signed, but will give you a warning on the Add-ons page if they are not.

Some extensions stopped working in Firefox 40 because the "widgets" module was removed. If you want to mention particular extensions that stopped working for you, a volunteer might have heard about whether a fix or update is available.

Specifically Norton ID Safe Standalone. I have updated it, uninstalled it, reinstalled it, installed an earlier version of Firefox, tried to enable the add on, now the add on is just gone, now the Norton ID safe says it's not even installed for firefox, and so I can't get it to reinstall the extension to even try again :( Glad I can disable that signing thing though! I have done as you said, it worked and I can use some of my add ons again!

Norton add-ons should work in Firefox 40, but I don't know about Firefox 41; Norton usually times its updates for the standard version, not the beta.

https://community.norton.com/en/blogs/product-update-announcements/firefox-40-support-norton-toolbar

Firefox should discover the toolbar through a registry entry created by the Norton installer. If found, it should appear on the Add-ons page either enabled, or at the bottom on the grayed section, disabled. If Firefox doesn't "see" it at all, there could have been a glitch with the reinstallation of Norton Identity Safe.

Yes, something has made Norton identity safe not install the add on at all, I just uninstalled and reinstalled it again however, it still has the exact same problem in that it is not installing the firefox extension at all. I have tried uninstalled/reinstalled both firefox and the norton id safe, neither worked the problem is still there

After writing the below suggestion, I noticed when you originally posted, you were running the 64-bit version of Firefox Beta. It's possible that extensions that use 32-bit binaries for some of their functions cannot run on 64-bit builds of Firefox, and there may not be any workaround for that. I don't know that to be the case with the Norton Toolbar/ID Safe, but it wouldn't surprise me knowing that the extension(s) need to be re-updated for each Firefox release.

When you uninstalled/reinstalled Firefox, I assume you kept your bookmarks and other personal data. In that case, I would try removing two settings files in case they are corrupted. Here's how:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Show Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > "power" button
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, then rename extensions.json to something like extensions_old.json. Also rename extensions.ini to something like extensions_old.ini.

Start Firefox back up again, and it should rebuild its extensions list. Does it find Norton this time?

I use a Hungarian Dictionary as an add-on. Firstly, I really don't understand why a dictionary needs to jump through hoops. In any case, I wrote to the developer, who replied that it is now all fixed. Sure enough, it got automatically re-enabled on my laptop (albeit a day after he told me that you have fixed it) I just discovered (a couple of days later still) that it is still disabled on my desktop. I even tried rebooting the computer, in case that will help, but no. Both of my computers are Win 7 64 bit. It is very frustrating!

Did you try to uninstall and reinstall the dictionary?