SCCM Current Branch - Updates and Servicing issue

I've been working with a customer this week upgrading ConfigMgr Current Branch to 1906. However I encountered a problem even before I got started.

In the ConfigMgr console. I could see that 1906 was available to download.

However all options were greyed out.

I've had similar problems in the past and the trusty CMUpdateReset tool usually got me out of trouble. However not this time. I ran the tool but the problem persisted. 1906 disappeared from the console but when it reappeared the options were still greyed out. 

There were some fairly catastrophic messages in the dmpdownloader.log file.

WARNING: Failed to find a certificate matching the following thumbprint: .

ERROR: DmpDownloader:GetMessages: Failed to get messages.. Exception: System.AggregateException: One or more errors occurred. ---> Microsoft.Management.Services.Common.NotSupportedException: {~~  "_version": 3,~~  "Message": "An error has occurred - Operation ID (for customer support): 926c3692-bde5-4c8d-a6fa-7297f93d226a - Activity ID: fb69f026-d17f-4bed-8c57-4a7ded103f37 - Url: https://fef.msub03.manage.microsoft.com/Hybrid/StatelessConnectorService/StateMessages?$filter=Mode eq 1&$top=500"

I don't know if there was an easier or less dramatic way to solve this but I fixed it by removing and re-adding the Service Connection Point (this is a perfectly harmless operation).

Normal service was resumed and I could upgrade the site.

I hope this helps. Until next time.....