Oracle Solution for Error ora-12850

ORA-12850: Could not allocate slaves on all specified instances: string needed, string allocated

What triggered the Error:

When executing a query on a gv$ fixed view, one or more instances failed to allocate a slave to process query.

What should we do to fix it:

Check trace output for instances on which slaves failed to start. GV$ query can only proceed if slaves can be allocated on all instances.