There is a Red Hat OpenStack bug description about the same error: https://bugzilla.redhat.com/show_bug.cgi?id=2015141. It looks like the servers were simply overloaded, i.e. it's not a bug.

On Tue, Feb 28, 2023 at 3:54 PM Parsa Aminian <p.aminian.server@gmail.com> wrote:

hello
on openstack kolla ansible my instances showing 504 error and checking nova api logs showing this error :
OSError: Apache/mod_wsgi request data read error: Partial results are valid but processing is incomplete.