Is your issue with Firefox 67 or Firefox 52? Your system details show that you are running Windows XP, which would mean that you are running at maximum Firefox 52. This dramatically changes the answer to your question.

In Firefox 57, Mozilla made the decision to only allow webextensions to be installed on Firefox. This was done to promote better performance and security. Any add-on that was not running the webextensions framework was labelled as a legacy add-on.

For more information on legacy extensions, see Frequently asked questions - Firefox add-on technology is modernizing.

In October last year, Mozilla also decided to remove legacy add-ons from their add-on listing website. This means that you can no longer download those extensions from there, although some developers still have legacy versions available.

This is where the answer will vary depending on the version of Firefox that you are running.

If you are indeed running Firefox 67 and have add-ons that are labelled as legacy, you need to download the latest versions. Nearly every add-on developer moved over to the webextensions framework and released new versions. I know for certain that LastPass and Adblock have working webextensions versions.

If you are on Firefox 52, as your system details information suggests, you should be able to run legacy add-ons without issue. In this case, what you are likely experiencing is the aftermath of the recent Firefox add-on issue that happened early last month.

In this case, you will need to download the patch for your version of Firefox. Since you are running an older version of Firefox, you have to manually install the fix because it's not being delivered to older versions automatically at this point.

Fixing this simply involves downloading the add-on fix for Firefox 52.

Hope this helps.

As I said initially, I'm talking about win7 and ver. 67. I couldn't post from that machine because I have LastPass unable to log me in. Because of the problems in May, I was afraid to re-download these add-ons because the blog post in May said not to with that situation. I still have two questions, one being, why are these labeled legacy with ver 67 and they were not in ver. 66? (And why weren't they upgraded?) Tomorrow I will download the two add-ons and post another reply. Hopefully all will work fine. Thank you for the quick response. Walt

Thank you Wesley. It took two tries to download LastPass and I learned that I had to remove the legacy add-ons first, but after half an hour, all seemed fine. I wanted to give it time before proclaiming victory, but it looks like all is well. Thanks again, Walt