With my—manually installed—Firefox 21, flash (and, therefore, YouTube etc.) suddenly stopped working. Again.
Some time ago, no printer was displayed in Firefox.
In both cases, problem was that Firefox looked up the plugin/driver in a directory that did not exist. Firefox 21 changed the plugin location from
, and the printer driver was not found a year ago since it was in
(when Debian changed the directory structure with 64-bit).
Strace is a nice console tool that traces system calls made by a program. System calls include file access! So let’s try, and filter the output for lines containing plugin:
Note the second access. This is where I extracted Firefox, and
is in the
subdirectory, but Firefox now needs it to be in
. Plugin moved, problem solved.
The solution for the printer problem works the same way. Filter the output for lines containing print, then open the printing dialog in Firefox. The solution is described here.