Thunderbird links will not start up Firefox
This comes up a lot on the internet and nobody ever seems to know a simple fix. I found this works almost 100% a while back.
The problem is, you have Firefox set as the default browser. Firefox is not running. You are using Thunderbird as your email client. You get a link in an email message and click on it ... but nothing happens. Firefox won't start. But if Firefox is ALREADY running, there is no problem.
It seems that something in the operating system registry loses the ability for Firefox to 'open' from the email client. I can't pinpoint why, but it seems to happen to people randomly from either a Windows update, a Firefox update, or a Thunderbird update.
So here is the simple 30 second fix that works almost every time:
Simply open IE and make it your default browser ... then go back and make Firefox your default browser again.
Problem solved
[Fix] Thunderbird links will not start up Firefox
[Fix] Thunderbird links will not start up Firefox
"Experience is something you don't get until just after you need it"
This issue doesn't seem to occur anymore, I'm pretty sure the topic can be unsticked.