ORA-12850: Could not allocate slaves on all

admin

ORA-12850: Could notallocate slaves on all specified instances: string needed,
string allocated
Cause: When executing a query on a gv$ fixed view, one ormore instances failed
to allocate a slave to process query.
Action: Checktrace output for instances on which slaves failed to start. GV$
query can only proceed if slaves can be allocated on all instances.