A Symantec DLP license file is about to expire or already has expired.
Release : 15.8 and newer
As of Symantec DLP 15.8 when a license file expires the related component will cease to function. I.e., if the endpoint prevent license expires, then the endpoint agent software will stop generating incidents, monitoring, blocking, etc., and the Enforce Server will no longer show the endpoint incident snapshots, nor the configuration options for endpoint agents. Along with that, no new agent packages can be created and any existing agent package used to deploy new agents will not function.
Similar rules will apply to Network Prevent for Web, or Network Prevent for E-mail Detection Servers. When the licenses expire the mail flow will not be interrupted but e-mails will pass through the servers without any detection or actions such as blocks.
More information can be found in the below article:
Maintenance Entitlement Overview for Symantec Data Loss Prevention (DLP) (broadcom.com)
Please note:
By default there is a 24 hour grace period on the licenses.