After modifying the TLS certificate used by the Control Center web interface in Administration > Control Center > Certificates, the old TLS certificate is still used by browser connections to the Messaging Gateway.
Messaging Gateway
The Control Center web application has not been restarted.
After modifying the certificate to be used by the Control Center web interface in Administration > Control Center > Certificates, the Control Center service needs to be restarted to load the updated certificate configuration. To restart the Control Center web application either:
service controlcenter restart