session attached to some other process; cannot switch session

Try the following links for this error:

http://docs.oracle.com/cd/E16655_01/server.121/e26079/e0.htm

https://community.oracle.com/message/116231

https://community.oracle.com/message/1443791

https://community.oracle.com/message/9273960

https://community.oracle.com/message/1444062

https://community.oracle.com/message/9446075

https://community.oracle.com/message/2025568

https://community.oracle.com/message/1193289

https://community.oracle.com/message/4497062

https://community.oracle.com/message/1117811

https://community.oracle.com/message/1228927

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