Bug report

If __DATE__ is undefined at build time (eg, CPPFLAGS=-U__DATE__), in the sys.version string, the date portion is set to xx/xx/xx. However the __DATE__ string follows MMM DD YYYY format.

platform._sys_version() does not know how to interpret xx/xx/xx, expecting MMM DD YYYY, so it raises an exception (ValueError: failed to parse CPython sys.version).

Your environment

• CPython versions tested on: exists from at least 3.8
• Operating system and architecture: irrelevant, any compiler where you can undefine DATE or it is not defined.

Linked PRs

• gh-100388: Change undefined __DATE__ to the Unix epoch #100389