Are these differences between the two servers are critical or may cause the issue?
working server OS >> ubuntu
the unworking server OS >> centos
and there are some other differences in the version of php and mysql
Maintenance or revision version changes - the 3rd value in the version should have no impact on sessions. It must be a difference in how the 2 servers handle sessions or something to do with MySQL, it's config, the data stored in the users table or etc...