Oracle OID Generation Failed - hankinsoft/SQLPro GitHub Wiki
When connecting to an Oracle database, you may receive the error message:
An error occurred while communicating with the Oracle Database data source '<data source name>'. Oracle database error 21561: ORA-21561: OID generation failed Unable to connect to the server "<server name>". Check that the server is running and that you have access privileges to the requested database.
If you receive this error message, please run the following command from terminal:
echo "127.0.0.1 $(hostname)" | sudo tee -a /etc/hosts
Once the command has been run, relaunch SQLPro and your Oracle connection should succeed.
References: