The full error is:
A SQL operation in the AD FS configuration database with connection string Data Source=np:\\.\pipe\microsoft##wid\tsql\query;Initial Catalog=AdfsConfigurationV3;Integrated Security=True failed.
Event ID: 352.
This was on Server 2016 with WID after I had done a Windows update.
The normal Google collection of mostly useless information when I searched.
The ADFS service was stopped. Restarting it just gave errors.
Then I came across a post where the user had restarted the "Windows Internal Database" service first.
I tried that - took a while - and then got an error message.
But when I looked at the status of the service it was running.
Restarting the ADFS service then worked - Hallelujah!
And the next thing I did was backup the database with the AD FS Rapid Restore Tool :-)