>>> import math, inspect
>>> inspect.signature(math.log)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/remi/src/cpython/Lib/inspect.py", line 3081, in signature
    return Signature.from_callable(obj, follow_wrapped=follow_wrapped)
  File "/Users/remi/src/cpython/Lib/inspect.py", line 2830, in from_callable
    return _signature_from_callable(obj, sigcls=cls,
  File "/Users/remi/src/cpython/Lib/inspect.py", line 2284, in _signature_from_callable
    return _signature_from_builtin(sigcls, obj,
  File "/Users/remi/src/cpython/Lib/inspect.py", line 2109, in _signature_from_builtin
    raise ValueError("no signature found for builtin {!r}".format(func))
ValueError: no signature found for builtin <built-in function log>
>>>

This is the only function from math to do so, it may be related to issue    29299 but the patch from Victor Stinner does not fix this.