N1QL: cbq.exe> select * from system:keyspaces; ←[31m ERROR 5000 : Post http://localhost:8093/query: dial tcp 127.0.0.1:8093: ConnectEx tcp: No connection could be made because the target machine actively refused it. ←[0m cbq.exe> cd

Open a power shell or cmd on windows.
Go to c:\program files\Couchbase\Server\bin directory
Open cbq prompt>
cbq.exe> select * from system:keyspaces;
←[31m ERROR 5000 : Post http://localhost:8093/query: dial tcp 127.0.0.1:8093: ConnectEx tcp: No connection could be made
because the target machine actively refused it. ←[0m

There is only 1 bucket default in the cluster and its empty.

I am able to execute the query from query tab.Also was able to create primary index on default using query tab.