Need help with firefox/thunderbird issue

Somehow i got firefox messed up. When i click links, for example in a thunderbird email, instead of opening the link, firefox opens the local cache file instead
I also get this for a kde popup message each time i click a link:
Copying Finished

I am sure this is something I have inadvertently done to myself but I cant seem to find and fix it. I tried restart in safe mode (both thunderbird and firefox) and it didn’t help

I have narrowed it down a bit. clicking a link in thunderbird has the same effect when either firefox or konqueror is my default browser - so its not a firefox browser issue
substituting prefs.js in ~/.thunderbird witha prefs.js from another pc that works ok didnt fix the issue so its not a prefs.js issue
I guess i need to remove ~/.mozilla and try it and if still bad try removing ~/.kde4 (or some relevant part of it anyways)

as far as I can tell from your post this is not a mozilla issue
prefs.js stores the user defined mozilla (firefox or tbird) preferences modified by an addon or by manualy tweaking about:config
you don’t have to copy it from a different pc you can just delete that file and mozilla will restore one with the default values


is not your firefox or tbird cache it’s your konqueror cache that’s why I’m guessing this is a konqueror issue I’m guessing Tbird sends the link to konqueror as an url file which konqueror extracts in it’s cache and then opens the default application url handler
I really don’t think using konqy as your default browser is a good idea for several reasons I think you should setup Firefox or Chromium as your default browser
you can delete your whole ~/.kde4 directory but that will just reset your settings for kde4 applications afaik on 42.2 that’s only konqueror and okular the rest are kf5 applications and that will not fix anything

Even with konqueror uninstalled I get the same results. I have always used firefox but was experimenting with konq to see if the same issue ocurred (it did)

I’d say see this

**Thank you I_A ! **The advice on that page fixed things (at least it appears to have in my very quick testing).
But, I didnt have to do this before, I sure wish I knew exactly what was wrong there - e.g the root cause