Sourcetree does not launch Beyond compare external merge tool

Question

Suddenly, when I try to launch "External merge tool" from Sourcetree, the tool does not appear. I say suddenly, because it worked last time I tried. The dialog remains forever:

Eventually I found this process related to the visual merge (dunno how to copy the command line from windows task manager):

This process, by the way, does not disappear when I press abort, so somebody probably didn't do their homework. Actually, I wouldn't probably notice it if there wasn't six same processes with this command line.

These are my settings:

How do I fix this? I need to merge project and I don't know what to do...

Answer 1

I found out that this happens when one of the files to be merged has been deleted. In that case, git prints out a command line prompt which sourcetree cannot handle. The git process then ends up hanging forever.

Best way to handle this is to kill the hanging git process and then make the choice manually using use mine/use theirs.