ADF connection issue with Cassandra

This usually happens because Azure Cosmos DB Cassandra API requires a secure connection (TLS/SSL) and the correct port. In ADF, the linked service doesn’t expose a simple “Enable SSL” toggle, but you can work around it:

Make sure you’re using the right port – Cosmos DB Cassandra API expects 10350 (not the default 9042).

In the linked service, the connection string needs to specify EnableSsl=true (sometimes you have to include it in the “additional connection properties” field).

Double-check that you’re using the username and password from Cosmos DB Keys (not a local Cassandra login).

Ensure your firewall/network rules allow outbound traffic on that port. Even though “All networks” is enabled, ADF still needs outbound reachability.

A lot of people hit this when ADF defaults to plain Cassandra settings. Adding SSL and the correct port usually fixes it.