Just create a new Repos, SourceTreee crashed and I cannot open anymore.

OK, got it! Analyzed the log an I can see "Illegal characters in path."

Unfortunately you cannot start SourceTree anymore any fix anything if you have this!

—
I have removed this line from opentabs.xml (see included):
<string>C:\Users\Public\Documents\Sync\Daten\GIT\pandoc.wiki</string>
and I could start again. Well!

Then I tried to add this local repository again (see pandoc.wiki.zip enclosed) and SourceTree crashed again. Origin of this WIKI repos is here: https://github.com/jgm/pandoc/wiki

May this all help you to identify the "illegal chars" which I expect to be in the repos and not in the config files.