Traditional client fails to communicate with SUSE Manager server after update of python2-rhnlib

SLE12 SP5 traditional client registered on SUSE Manager server gets updated with the newest packages, where python2-rhnlib-5.0.3-21.49.1 is the newest version. The next update or refresh will fail however then with the below error found in the client's "/var/log/up2date" log file:

up2date 
Traceback (most recent call last):
  File "/usr/sbin/rhnreg_ks", line 223, in <module>
    cli.run()
  File "/usr/lib/python2.7/site-packages/up2date_client/rhncli.py", line 91, in run
    sys.exit(self.main() or 0)
  File "/usr/sbin/rhnreg_ks", line 94, in main
    rhnreg.getCaps()
  File "/usr/lib/python2.7/site-packages/up2date_client/rhnreg.py", line 265, in getCaps
    s.capabilities.validate()
  File "/usr/lib/python2.7/site-packages/up2date_client/rhnserver.py", line 67, in __call__
    return rpcServer.doCall(method, *args, **kwargs)
  File "/usr/lib/python2.7/site-packages/up2date_client/rpcServer.py", line 217, in doCall
    ret = method(*args, **kwargs)
  File "/usr/lib64/python2.7/xmlrpclib.py", line 1243, in __call__
    return self.__send(self.__name, args)
  File "/usr/lib/python2.7/site-packages/up2date_client/rpcServer.py", line 48, in _request1
    ret = self._request(methodname, params)
  File "/usr/lib/python2.7/site-packages/rhn/rpclib.py", line 449, in _request
    self._host, self._handler, request, verbose=self._verbose
  File "/usr/lib/python2.7/site-packages/rhn/transports.py", line 200, in request
    headers, fd = req.send_http(host, handler)
  File "/usr/lib/python2.7/site-packages/rhn/transports.py", line 882, in send_http
    self._connection.connect()
  File "/usr/lib/python2.7/site-packages/rhn/connections.py", line 239, in connect
    self.sock.init_ssl(self.host)
  File "/usr/lib/python2.7/site-packages/rhn/SSL.py", line 101, in init_ssl
    self._ctx = SSL.SSLContext(SSL.PROTOCOL_TLS_CLIENT)
<type 'exceptions.AttributeError'>: 'module' object has no attribute 'PROTOCOL_TLS_CLIENT'

On the affected client downgrade to the previous python2-rhnlib-4.3.5-21.46.1 package version manually, or install the mass-PTF from the below link:

https://ptf.suse.com/2/f2cf38b50ed714a8409693060195b235/susemanager-client-tools-12/28414/x86_64/20240729

"PROTOCOL_TLS_CLIENT" has been added in python 3.6 and some older registered clients like SLE12 SP5 still use python 2.7 with "PROTOCOL_TLS".

PTF how-to:

https://www.suse.com/support/kb/doc/?id=000018572

In case of registering new clients, salt is the recommended management method since the traditional stack is deprecated and will not be used in the future.