Hello all -
I have been doing some testing and can replicate the "An error has occurred" issue you are seeing when trying to add a custom location type. It does seem to occur when a user does not have administrator rights to the local PC. We are looking at changing the way this works in future versions, but no decisions have been made at the current time.
For the time being, the workaround is to have an administrator grant the user full read/write permissions to the c:\Program Files (x86)\EsriMaps folder and all files and subfolders within. In local testing this fixed the issue on my test machine and I was able to add custom location types. Please let me know if this workaround solves the problem for you.
Thanks,
Scott