How to fix python ipaddress.IPv6Address AddressValueError: Unexpected ‘/’ in ‘…/64’


When trying to parse an IPv6 network address in Python using code like

import ipaddress

you see an error message like

AddressValueError                         Traceback (most recent call last)
/tmp/ipykernel_154945/ in <module>
----> 1 ipaddress.IPv6Address("2a01:c23:c0bb:d00:8ce6:2eff:fe60:cc69/64")

/usr/lib/python3.8/ in __init__(self, address)
   1836         addr_str = str(address)
   1837         if '/' in addr_str:
-> 1838             raise AddressValueError("Unexpected '/' in %r" % address)
   1839         self._ip = self._ip_int_from_string(addr_str)

AddressValueError: Unexpected '/' in '2a01:c23:c0bb:d00:8ce6:2eff:fe60:cc69/64'

Solution 1: Remove the CIDR netmask (/64)

By just removing the slash and the part after it (the CIDR netmask).

Solution 1: Maybe you should use IPv6Network instead of IPv6Address

If you intend to parse the network, use ipaddress.IPv6Network but remember that this will discard all host bits. If you want to use IPv6Address or IPv6Network really depends on what you want to do with it – if you want to refer to a specific host, you almost always want to use IPv6Address.

import ipaddress
ipaddress.IPv6Network("2a01:c23:c0bb:d00:8ce6:2eff:fe60:cc69/64", strict=False)

Note that strict=False is added in order to prevent an exception due to host bits being set – see How to fix Python ipaddress.IPv6Network ValueError: … has host bits set