IBM Firefox failed to be updated

Just for the record, IBM does not develop Firefox. It's just a rebranded version of Firefox ESR, still pure Mozilla.

When installing Mac@IBM App Store (MIAS), the IBM Firefox got installed along the way, however much you like the vanilla Firefox and reluctant you feel for the customised version. For the past few days it kept reminding me of updating to the version 31.8.0. But every time I opened the update dialog and let it proceed, it stuck at contacting the update server. The same symptom has been reported a lot in the IBM Apple / Mac Community, until I found this one.

It turned out that /Applications/IBM Firefox.app is owned by root. No wonder it couldn't be updated when running by an unprivileged user. After running the following command and launching Firefox again, it was successfully updated!
sudo chown -R tony:staff IBM\ Firefox.app


Update 2015/09/18: I've been setting up another MacBook Pro these days and found happily that MIAS now installs Firefox with correct permissions.