Using the The Microsoft Error Lookup Tool - Win32 apps | Microsoft Docs, code 246 matches two different results depending on whether it is hex or dec.
# for decimal 246 / hex 0xf6
PCI_VERIFIER_DETECTED_VIOLATION bugcodes.h
# for hex 0x246 / decimal 582
ERROR_ILLEGAL_CHARACTER winerror.h
# An illegal character was encountered. For a multi-byte
# character set this includes a lead byte without a
# succeeding trail byte. For the Unicode character set this
# includes the characters 0xFFFF and 0xFFFE.
# as an HRESULT: Severity: SUCCESS (0), FACILITY_NULL (0x0), Code 0x246
# for hex 0x246 / decimal 582
ERROR_ILLEGAL_CHARACTER winerror.h
# An illegal character was encountered. For a multi-byte
# character set this includes a lead byte without a
# succeeding trail byte. For the Unicode character set this
# includes the characters 0xFFFF and 0xFFFE.
# 3 matches found for "246"
If you were having a PCI_VERIFIER_DETECTED_VIOLATION issue, I am guessing you would be seeing a whole lot more problems, maybe even a BSOD. So, that leaves the illegal character and the likely culprit.
What program did you create your Python script in? Did you copy and paste the code from somewhere?
Or, it could just be something got corrupted with Python when you installed/upgraded to Pro 2.5. You could always try uninstalling and reinstalling Pro.