When I use this line in x-path: MonthNumber=month-from-dateTime('[%CurrentDateTime%]' It gives me this error 'data type cast needed for parameter or null literal' while I expect for example month-from-dateTime('[%CurrentDateTime%]' to return 2 (current month number).
Probably this is a built-in-database (HSQLDB) only issue. For PostgreSQL, this constraint runs fine.
However, you can also create a microflow variable, set the value to the current month and use this variable in the XPath constraint.
I believe it requires an actual DateTime attribute.