The internal format used for source sites recently changed (there is now a surf_id attribute that is used for surface source reading/writing). I’m not sure how you are creating the ADS source file, but if you are using openmc.write_source_file, you should make sure that you use that function from the same version of OpenMC that is used to eventually read the source file.
Either way, running into a segfault is not ideal behavior. I’m working on adding a check on the source file format to ensure that it matches what OpenMC expects. If it doesn’t match, an error message explaining what is wrong with it will be displayed.