I ran into a nasty little bug in Mozilla Firebird trying to install extensions. Any time I tried to install extensions, the install would fail and I’d receive “error code -239, chrome registration failed.” I’ve been trying to fix this problem for a while; it was driving me batty!
Turns out, this is a known bug with Mozilla Firebird under UNIX systems (including Linux). One poster to the bug thread found a solution for Debian systems: change permissions on all files in /usr/lib/mozilla-firebird and /var/lib/mozilla-firebird. The problem is caused by Debian’s default permissions for these two directories. Debian sets the owner to root for these folders.
On most systems, the work-around for this would be to install extensions to a user’s profile directory. Unfortunately, Firebird still needs to make changes to the /var/lib/mozilla-firebird directory, so the operation still fails. At a minimum, permissions on /var/lib/mozilla-firebird need to be changed to allow writing.