I've somehow managed to break firefox:
- Random downloads fail
They appear in the download manager with "failed" next to them.
Copying and pasting the URL and fetching via wget works.
- Random extensions fail to install.
"Ghostery could not be installed because firefox cannot modify the needed file".
Moving ~/.cache/mozilla and ~/.mozilla out of the way don't help. Installing "tree style tabs" fails with no particular error.
The actual error reads "The extension couldn't be installed because firefox couldn't modify the needed file".
Googling didn't help, because it says "Create a new profile", which doesn't help, or "Disable extensions", which doesn't apply since none are present in the new profile.
Running strace doesn't reveal any obvious EACCES, EPERM, or ENOENT errors so I'm struggling to spot an obvious problem.
Downloading a binary firefox to /opt/firefox fails in the same way. Logging out of my desktop fails to make any difference.
The only thing I can say is:
shelob ~ $ dpkg --list | egrep '(xul|icewea)' ii iceweasel 29.0.1-1~bpo70+1 ... ii xulrunner-29 29.0.1-1~bpo70+1 ...
For the moment I'm hating the use of chromium, but it will suffice until I can try to dig deeper.