The relevant plugins seem to be located in /usr/lib/x86_64-linux-gnu/gegl-0.4 (on my machine), so I did a: dpkg -S /usr/lib/x86_64-linux-gnu/gegl-0.4/*to find where each file was coming from. As it happens, most were coming from the libgegl-0.4-0t64 package, but a few were not. Some of these had names that hinted at them being leftovers from an improperly cleaned up upgrade. I removed them (actually renamed them to ${name}.disabled), and now GIMP starts.*phew*2/2