In file /opt/sagemath-9.3/local/lib/python3.7/site-packages/sage/groups/generic.py, line 468, the arguments of function multiple is missed. That makes the bsgs calculation in customized group raise ValueError. Fixing this bug is simple. Just add the missing arguments is ok, like this: c = op(inverse(b), multiple(a, lb, operation=operation, identity=identity, inverse=inverse, op=op))