Cause
When executing a query on a gv$ fixed view, one or more instances failed to allocate a slave to process query.
When executing a query on a gv$ fixed view, one or more instances failed to allocate a slave to process query.
Check trace output for instances on which slaves failed to start. GV$ query can only proceed if slaves can be allocated on all instances.
Try the following links for this error:
http://docs.oracle.com/cd/E16655_01/server.121/e26079/e12700.htm
https://community.oracle.com/message/4531253
https://community.oracle.com/message/10194028
https://community.oracle.com/message/1799292
https://community.oracle.com/message/10794066
https://community.oracle.com/message/3352388
https://community.oracle.com/message/9430941
https://community.oracle.com/message/1679620
https://community.oracle.com/message/1946620
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