# Limitations of certificates

Certificates used in system communications become invalid when the certificate authority changes.

The internal certificate authority can change if the Management Server is reinstalled and the configuration is recreated manually or by importing elements instead of importing a backup. Management Server backups contain certificate authority information. If backup restoration is not an option, all SMC components must receive a new certificate for system communications.

In some cases, restoring the Management Server backup might also cause the internal certificate authority to be different from the certificate authority that was used to create certificates for some components. The invalid certificates must be replaced with new ones.