Issue

After upgrading Tableau Server, previously working extracts pointing to DB2 on iSeries using an ODBC Connection, the refresh fails with the error "Check the Data Connection page for necessary updates to an access token or embedded credentials"

• The following errors will appear in the Tableau Server logs at Logs/Backgrounder/Backgrounder.log:
  • (,,,) scheduled-background-job-runner-1 : ERROR com.tableausoftware.backgrounder.runner.BackgroundJobRunner - Error executing backgroundjob: :refresh_extracts java.util.concurrent.ExecutionException: com.tableausoftware.nativeapi.dll.DataSourceException: Tableau was unable to generate a query to perform this operation.
• The following errors will also appear Tableau Server logs at Logs/Vizqlserver/Logs/Backgrounder.txt:
  • Unable to connect using the DSN named ",<iSeries Server Name>". Check that the DSN exists and is a valid connection AND
  • Connected to Generic ODBC version \"07.01.0015\", recognized as \"7.1.15\" AND
  • DataSourceException (type=Unknown): [IBM][System i Access ODBC Driver][DB2 for i5/OS]SQL0104 - Token <END-OF-STATEMENT> was not valid. Valid tokens: + - AS <IDENTIFIER>.\n AND
  • GenericODBCConnection::CheckTopSupport: failed to detect top style via SQLRelationCheckTop. Capability customization may be required

• Tableau Server
• ODBC
• iSeries DB2

Connecting to an IBM DB2 data source on iSeries platform is currently not supported. However, you may have some success connecting to this data source on the ISeries platform using the following suggestions: 

• Create a TDC  file with the customization named CAP_SUPPRESS_DISCOVERY_QUERIES and set to 'yes'. This Tableau Community Blog Post walks through that process: https://community.tableau.com/people/bryant.howell.0/blog/2014/08/21/iseries-db2-odbc--enabling-multiple-tables-and-custom-sql
• Mirror the data source onto a supported data source. When working with DB2 data sources on the iSeries platform, you can mirror the data source onto a supported data source like pSeries or xSeries platforms, and then connect to the database using the native DB2 data connection

For more information about the capabilities and limitations of connecting to unsupported data sources using the generic ODBC connections, see Tableau and ODBC and Customizing and Tuning ODBC Connections