When attempting to log onto a Data Domain's management webpage, sometimes you may run into the issue where you are not able to log on, and the following error appears, even though you have not upgraded the firmware or there's nothing wrong with installed SSL certificates.

Service Not Available

The GUI Service is temporarily unavailable. Please refresh your browser. If the problem persists, please contact DataDomain support for assistance.

While the webpage does not work, it is still possible to log on using CLI (through SSH).

If you have not upgraded DDOS, try restarting the web services by logging on through CLI and running the following commands in sequence:

adminaccess disable http
adminaccess disable https
adminaccess enable http
adminaccess enable https

Wait for a few minutes to allow the web services to start completely. Then try to connect again.

If you see this error after a DDOS upgrade, you may need to generate a new self-signed certificate. Log on through CLI and run the following commands in sequence:

adminaccess disable http
adminaccess disable https
adminaccess certificate generate self-signed-cert
adminaccess enable http
adminaccess enable https

Wait for a few minutes to allow the web services to start completely. Then try to connect again.