Tableau Prep Flows fail to run intermittently with error "AqlProcessor evaluation failed:[SQLSTATE:HY000]" on Tableau Server

Issue

Tableau Prep Flows published on Tableau Server fail to run intermittently with error "AqlProcessor evaluation failed: [SQLSTATE:HY000]".

Environment

Tableau Server 2021.1 and earlier

Resolution

Upgrade to Tableau Server 2021.2 or later

Cause

This is a known issue that is fixed in more recent version of Tableau Server

Additional Information

Below exception will be noticed in flowprocessor logs
floworchestration: ERROR com.tableau.loom.nativeapi.grpc.NativeLoomApiGrpcImpl - SelectIntoAsync: Exception in WaitForAsyncRun:
java.lang.RuntimeException: AqlProcessor evaluation failed: [SQLSTATE:HY000]