Cause
The user attempted to modify a SQL Tuning Set or to add a reference to a SQL Tuning Set which is in use.
The user attempted to modify a SQL Tuning Set or to add a reference to a SQL Tuning Set which is in use.
Wait until the end of the previous operation and retry.
Try the following links for this error:
http://docs.oracle.com/cd/E16655_01/server.121/e26079/e12700.htm
https://community.oracle.com/message/3229900
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