Does this error come up every time or just periodically? Was this working before or is this the first time it's been tried? Just a first glance at the error message looks like the Tableau Server might lack permission to access the correct database on the server named "TNKNXS-APPS04". A look into the logs to see where that request ID (the number that starts with V-P5t..) goes would likely shed some light on the situation as well.
Hope this helps!
The displayed error message is supplying you with the reasons why it has failed! Answer those error messages first and you'll likely get your answer.