I spent some time over the weekend upgrading my son’s F9 machine to F10 and chose the PreUpgrade path. It all went well and when I finally logged into the F10 environment, Firefox refused to run saying that it “Couldn’t load XPCOM”. Did a search for similar reports and all of them, unfortunately, were rather sparse in information. I decided to do the following:
a) rpm -e firefox
b) yum search mozilla
The search yielded some clues – xulrunner among others. So, the following was done:
c) yum -y reinstall xulrunner*
d) yum install firefox
and when it was all said and done, ff fired up happily!