Oracle Error Codes

cannot call this function from a non-master process

Called a Data Pump process model function from a process which is not a master process.

How to Solve :

Create a master process first. Then call the function from the master process. If this error occurs from a Data Pump client (e.g. expdp or impdp), try the operation again. If the error occurs again, contact Oracle Customer Support and report the error.