Querying from system.schema_keyspaces generates code=2200 [Invalid query] I'm following Cassandra docs to learn CQL but when I type the query 
SELECT * from system.schema_keyspaces; the system generates 
InvalidRequest: code=2200 [Invalid query] message= unconfigured table system.schema_keyspaces. Although I'm able to execute another quires like create, update..etc.
The issue you are having here, is that you are using docs to explore Cassandra that are for version 2.0 and 2.1.  My guess is that you are probably using Cassandra 3.0.  In that case, you will need to query the system_schema keyspace for the "keyspaces" table:

cassandra@cqlsh:system_schema&gt; SELECT * FROM system_schema.keyspaces;

 keyspace_name      | durable_writes | replication
--------------------+----------------+----------------------------------------------------------------------------------------
               test |           True | {'PowerWindows': '1', 'class': 'org.apache.cassandra.locator.NetworkTopologyStrategy'}
        system_auth |           True |    {'class': 'org.apache.cassandra.locator.SimpleStrategy', 'replication_factor': '1'}
      system_schema |           True |                                {'class': 'org.apache.cassandra.locator.LocalStrategy'}
 system_distributed |           True |    {'class': 'org.apache.cassandra.locator.SimpleStrategy', 'replication_factor': '3'}
             system |           True |                                {'class': 'org.apache.cassandra.locator.LocalStrategy'}
      system_traces |           True |    {'class': 'org.apache.cassandra.locator.SimpleStrategy', 'replication_factor': '2'}

(6 rows)


Cassandra underwent a major storage engine rewrite for 3.0+, so much of the schema interactions are different as of that version.  In the future, be sure to double-check valid documentation versions with your local Cassandra version.  From cqlsh, you can query that:

cassandra@cqlsh:system_schema&gt; SELECT release_version from system.local;

 release_version
-----------------
             3.4

(1 rows)