It is most likely to be an error in a calculated condition in your process and this sort of error typically occurs because the calc has insufficient null checking.
ie say your calc does this...
if mycategoryobj.fullname == ‘xyz123’:
... but you havent set the category field at the point the calc runs then you’d get this sort of ”XML(1,1)” error.
so instead you’d trap the null object first and because logical tests support ”short-circuiting” you could do...
if mycategoryobj != null and mycategoryobj.fullname == ‘xyz123’:
You can get away with not null checking some objects (status, class, etc) as they are always set by the system but others need to be checked for nulls to be safe.
In your case turn on diagnostic logging for calcs in ConfigurationCenter and create the error again and check the log file to give you a better clue of the calc that is failing.