Config will not open after Buildbot2 upgade from 2.9.4 to 2.10

I think you never expected somebody to upgrade a sim. Normally you would just reinstall it but in this case, but there was a reason.
The biggest issue, is that there is a total lack of error logging and even the error window does not report that it is a QTplasmac message. eg. It could have belonged to the Linuxcnc core, qtvcp or qtplasmac. I had no idea. 

I think its worth fixing sooner than later becasue once Andy has sorted out his 64 bit integers, he will release 2.10 and then there will be crowds of people upgrading from 2.9.x to 2.10, so more chance of problems.