[Qgis-user] Processing Update: GRASS not working in the toolbox

[Bernd Vogelgesang]

Hi,
I'm going nuts! It took me weeks till a got a working QGIS 2.8 install  
with GRASS(7) working in the toolbox on Linux Mint/Ubuntu.

Using the model builder to create some workflow, I became aware that there  
is a Processing update available.
Doing this update, the model doesn't work anymore, cause GRASS stopped  
working in the toolbox.

When I do a fresh install without updating Processing, I get an error when  
I try loading my model (which I unfortunately saved with the new  
Processing version).

Ok, I could create that model again with the non-updated Processing  
version, so the GRASS function I need is available, but I also rely on the  
new "OGR Dissolve Polygons" function introduced with the new Processing  
version, cause I need to sum up an attribute while dissolving, and there  
is no alternative function at hand.

Anyone an idea what to do? Seems I'm caught in kind of a time/version hole.

Cheers
Bernd