Sorry, if you have the Office suite this problem can arise when switching from the 32-bit to the 64-bit version of Firefox. There is a link in the following article to an Outlook/Exchange site that may have a solution: How to switch from 32-bit to 64-bit Firefox.

Hi jscher2000 Many thanks for your reply. I have now determined that I have both Windows and Firefox 64 bit systems. But I cannot find the link anywhere in the article that you mentioned that directs me to an Outlook/Exchange site. Sorry if I'm being dim - please could you show me where to find it. Many Thanks Cheers Jon

Sorry, the article was updated since I saw it last.

https://www.slipstick.com/problems/this-operation-has-been-cancelled-due-to-restrictions/

Hi again jscher2000

And thanks again, but ...

I have tried one of the solutions that suggested changing the junk mail settings - it didn't work. I have tried the solution to change all the relevant registry data settings to htmlfile - this didn't work either. I have uninstalled and re-installed both Chrome and Firefox - this doesn't work. The solution offered in the copy/paste that I've put below doesn't apply since my versions of Windows and Office do not use Internet Explorer, they use Edge. "I found that re-installing Google Chrome or FireFox and setting it as the default, the hyperlinks worked. I then went to Internet Explorer and set it as the default browser. I again checked the hyperlinks, and again they worked. I then un-installed Google Chrome and have had no problems since. Hopefully this will work for others as well."

I'm completely stumped - what next?

Windows 10 has updated dialogs for associating a program with a protocol. I'm attaching a screenshot of what I have in Windows 7 in case it's useful. Can you successfully set the associations for HTTP and HTTPS to Edge?

Okey dokes I've done that - what do I do next?

(Huge thanks for the help)

Does it work with Edge? You may be able to set it back to Firefox once Outlook is happy.

Sorry no, it doesn't work with Edge either. I set Edge as my default browser but it didn't work. And I reset Firefox back to be my default browser and it still doesn't work. Think I'll try the same routine with Chrome and see what happens. Will first reset the http and https to Chrome. Starting to go round in circles here ... Really appreciate you trying to help me - big thanks. Cheers Jon

Tadaaa - it worked with Chrome. Along with HTTP and HTTPS I also reset the FTP to Chrome, it was still set to Firefox. And now the hyperlinks in my Outlook emails work. Now to see if I can fiddle it all back to Firefox - not really a Chrome fan but I suppose I could find out how it works and get used to it if I have to. Gonna let my laptop go to sleep on the new settings for a while (me too) I'll do my fiddling in the morning. Thanks for all the help Cheers Jon

And then I made Firefox my default browser without changing anything else and the hyperlinks in Outlook still work. Problem solved. Huge thanks for all your help. Cheers Jon

I'm glad to hear it's solved. Sorry Firefox couldn't do that on its own without help from other browsers. There's some magic Mozilla needs to learn from Google apparently.