In most of Dynamics 365 deployments on-premises a repetitive error occurs for MSCRMMonitoringTest and MSCRMKeyGenerator, like this:

Monitoring test failed: Test Title: Verify active crm keys exist for the deployment.: Machine: MyServer: ServerRole: AsyncService
Test Log: Key ‘CrmTicketKey’ is not activeKey ‘CrmWRPCTokenKey’ is activeKey ‘CrmEmailCredentialsKey’ is activeKey ‘CrmTicketKey’ is not activeKey ‘CrmStaticVersionScaleGroupKey’ is activeKey ‘CrmWRPCTokenKey’ is active.

The current active key (KeyType : CrmTicketKey) is expired. This may indicate that a key is not being regenerated correctly. Current Active Key : CrmKey(Id:c16aa9a1-35f1-e711-80ed-0050568e123d, ScaleGroupId:00000000-0000-0000-0000-000000000000, KeyType:CrmTicketKey, Expired:True, ValidOn:01/04/2018 09:57:11, ExpiresOn:01/06/2018 09:57:11, CreatedOn:01/04/2018 09:57:11, CreatedBy:DOMAIN\Service_Account. Key Setting : CrmKeySetting(Id:15f469b3-5f58-4b3d-a539-6b0e9d23a67c, KeyType:CrmTicketKey, KeyLength:128, KeyGenerationInterval:24, KeyTimeToLive:48, CryptoTimeToLive:24, Algorithm:HMACSHA256, ArchiveLength:1, Enabled:True, ActiveKeys:[ScaleGroupId=00000000-0000-0000-0000-000000000000,ActiveKeyId=c16aa9a1-35f1-e711-80ed-0050568e123d])

This is a known issue (bug) and will be fixed in future updates. Unfortunately, I work on this with Microsoft since November last year and we have not yet received a solution for it. The known workaround like restart MSCRMMonitoring service or the manual key renewal with the Microsoft tool Microsoft.Crm.Tools.WRPCKeyRenewal.exe /R or manual cleanup of old keys at database does not help for long time.

The good news: It does not take effect on the system and this causes no issues while running the application.