How to Resolve ORA-12850: Could not allocate slaves on all specified instances: 2 needed, 0 allocated

JDBC ORA-12850

Some developers report ORA-12850 error in their JDBC log.

ORA-12850: Could not allocate slaves on all specified instances: 2 needed, 0 allocated

There could be many ways to solve this, but I run the following statement to remove ORA-12850.

SQL> alter system flush shared_pool;

System altered.

For a RAC system, you should flush shared pool on other nodes, too.

In this way, we don't have to restart the database.

Toad ORA-12850

Met an error when I tried to monitor the database by querying sessions in Toad for Oracle.

To work around the error, we should prevent Toad to allocate slave processes on other node in this moment, you can uncheck "Use RAC Views" like this.