Thanks for the question!  Based on what you’re saying, I think you likely have some expired licenses.  Though this can happen for any client, it will often present when running backups or restores either for the first time, on clients that have temporary/eval licenses, or clients that have multiple iDAs.

The error indicates that the Agent for that subclient is not licensed, and therefore cannot run. There are a few scenarios common to this issue:

1. The installation used an eval license that has since expired
2. This is a brand-new installation and there is not an available license for this iDA
3. A Schedule is kicking off backups for every subclient on this client, even though they are not licensed (and usually not run)

The error message will provide the name of the client and the agent that is not licensed.

Run a License Summary Report and find the client in question, taking care to specifically notw the Agent type in the error string:

https://documentation.commvault.com/commvault/v11/article?p=105350_2.htm

It's important to differentiate between the agents since a client can be licensed for one iDA, but expired for another (i.e. the Windows iDA is licensed, but the Microsoft SQL iDA is not which is the source of the error).

If the license is expired or missing and you have extra licenses for that agent, then follow the directions below to Reconfigure:

Reconfigure:
https://documentation.commvault.com/commvault/v11/article?p=5955.htm

If there's a need to deconfigure an unused agent to free up a needed license, or you wish to deconfigure and reconfigure the agent in question, follow the directions here:

Deconfigure:
https://documentation.commvault.com/commvault/v11/article?p=5945.htm

To convert an expired license:
https://documentation.commvault.com/commvault/v11/article?p=6996.htm

Same issue Here today.

I released the License on File System → FS turned grey

Then i reconfigured it and run Full Backup on FS.

It helped