cqlsh connection error: 'ref() does not take keyword arguments'

refer https://issues.apache.org/jira/browse/CASSANDRA-11850

After setting environment variable

CQLSH_NO_BUNDLED=TRUE

it resolved.

I use windows 7, python 2.7.12, cassandra 3.7

You are running into CASSANDRA-11850, where cqlsh breaks with Python 2.7.11+. This ticket has been marked as "Resolved" and a patch has been applied to Cassandra 3.9 which has not been released yet.

I believe I installed all the necessary packages such as java 8 and python 2.7.12.

In the interim (until 3.9 is released) you can roll back to Python 2.7.10, and cqlsh should work (not trivial). Otherwise, DataStax DevCenter should work with Cassandra 3.7.

Edit 20161020

Cassandra 3.9 was released a few weeks ago, and can now be downloaded.