It looks like "LinkmanFox" is only available directly from Outertech, not on the Mozilla Add-ons site.

Judging from the .xpi file I downloaded from https://www.outertech.com/en/firefox-bookmark-manager, it hasn't been updated since 2017. However, it needs to be re-signed with the current certificate. (https://extensionworkshop.com/documentation/publish/signing-and-distribution-overview/)

Can you submit a request to the company to do that ASAP?

That will probably take at least a few days since it's the weekend. If you need a temporary workaround, I can suggest using the Add-on Debugging feature. This is only good until you quit Firefox; you'll need to do it again for your next session. However, it might be worth it if you use the extension heavily. Let me know if you're interested.

Sneak peek: https://firefox-source-docs.mozilla.org/devtools-user/about_colon_debugging/index.html#loading-a-temporary-extension

Many thanks for a quick response. Did bring to the attention of linkman. Not sure when they will fix it. I really would like to do the work around. Please let me know how to proceed.

Many thanks.

Sure.

File Setup

The goal is to grab a copy of the extension and paste it in a convenient location, then extract its files.

This assumes you have a program for unzipping ZIP archives, such as 7-zip, WinZip, etc.

(1) Open https://www.outertech.com/en/firefox-bookmark-manager (2) Find the paragraph below "Problems installing Linkman.xpi file?" (3) Follow the steps to Save Link As, but use the Downloads folder instead of your desktop to keep things tidier (4) Use the Downloads button on the toolbar to go to the folder (the icon on the right side next to the file name) (5) An XPI file is a ZIP file internally. Use your unzip program to extract the contents of the .xpi file to a new folder.

Loading the Extension Into Firefox

(1) Type or paste about:debugging in the address bar and press Enter to load the page (2) In the left column, click This Firefox -- you might want to bookmark this page for future access (3) Click the Load Temporary Add-on button (4) When Firefox pops up a Windows file browser, go to the folder which holds the files extracted from the XPI and double-click manifest.json (5) Assuming no errors are displayed, the extension is running

Sorry could not get back earlier. Did everything per your excellent instructions, however, I still don't see the linkman icon in my bar as before? Not sure why?

Thanks again.

Many, many Thanks, I am now able to see the icon. Had missed step to show it. 5 stars out of 5!

Hi again, your solution worked a bit but it no longer works. Yes i have gone through the procedure every time ff starts but now it does not work for some reason. I am not sure even if linkman still exists, as I did not get a response from from them as yet. Thanks for your help.

I am not aware of a good alternative. Submitting the extension to the Mozilla Add-ons site to get a personal signed copy takes many days. https://extensionworkshop.com/documentation/publish/signing-and-distribution-overview/

OK many thanks will wait and see.