module 'lib' has no attribute 'X509_V_FLAG_CB_ISSUER_CHECK'

In odoo 15, you might receive X509_V_FLAG_CB_ISSUER_CHECK error after installation.

I is a incompatibility of pyopenssl and  cryptography version.

Based on requirements.txt file there is a comment on cryptography about this incompatibility  as you can read it hear:

cryptography==2.6.1  # incompatibility between pyopenssl 19.0.0 and cryptography>=37.0.0