Error Validating a Query "relation does not exist"

Products

• Clarity FedRAMP
• Clarity PPM On Premise
• Clarity PPM SaaS

Issue/Introduction

You get an error when validating a query in the Administration > Queries, for any query:

This query cannot be validated.
Please correct the following items and revalidate.
Invalid Query: 
SQL error code: 0
Error message: ERROR: relation "<relation>" does not exist [...]

Environment

Clarity 16.4.2

Cause

As the issue described is related to any query, the likely cause is some DB read only user permissions missing.

Resolution

Review permissions for the DB to ensure that the user is able to run SELECT queries.