If both Firefox and Icecat Browser (from Gnu) are installed, Icecat's icon is used for Firefox in the task manager. If Icecat is uninstalled and I log out and back in then run Firefox, the Firefox icon is used even after I reinstall Icecat. However, if I ever launch Icecat before I launch Firefox the problem is back and Firefox has Icecat's icon again. After the "fix" of uninstalling Icecat, logging out and in, starting Firefox then reinstalling Icecat the only way to prevent the problem from returning is to always launch Firefox before running Icecat, every time.
Happens for all users. Happens with both the Task Manager and the Icons-only Task Manager.
I have Plasma 5.10.2-1, my Linux distro=PCLinuxOS64-kde5-2017.06.20, fresh installation as of four or five hours ago.

Quick fix:
right click on app launcher - edit applications - select firefox - assign correct icon

toad wrote:Quick fix:
right click on app launcher - edit applications - select firefox - assign correct icon

That fixed it after restarting Firefox. I want to test it some more to see if the fix "sticks" before marking this solved though.

jaymot wrote:

toad wrote:Quick fix:
right click on app launcher - edit applications - select firefox - assign correct icon

That fixed it after restarting Firefox. I want to test it some more to see if the fix "sticks" before marking this solved though.

After testing it for a day your fix is still working. Firefox hasn't reverted back to the Icecat icon no matter in what order I launch the two browsers. Thank you.

Cool. Don't know the cause, though.

Could you mark the topic as solved?

Cheers