One of the problems that I had with FireFox (126.96.36.199) on Kubuntu was that on the download manager window, neither “Open” or “Open Container folder” worked. I clicked and clicked and nothing happened. A lot of people complains about this issue on the Firefox bug tracker database, where it seems that this issue only happens with 32bit version on Firefox. Bummer for my computer to be 6 years old… 🙂 (And it runs Linux!)
As usual Google helped me to find a solution, but with one caveat: The icons on the left side of the bookmarks are lost or changed to the same icon (In this case Konqueror).
What I did was:
1) On the address toolbar write the following: about:config
2) Right click on the page and choose new->string
3) Write the following value: network.protocol-handler.app.file
4) After pressing Ok, double click on the new entry and write: /usr/bin/konqueror
Now try it. It should work now.