Amazon Redshift will no longer support the creation of new Python UDFs starting November 1, 2025. If you would like to use Python UDFs, create the UDFs prior to that date. Existing Python UDFs will continue to function as normal. For more information, see the blog post .

Connection fails

Your query connection can fail because for the following reasons. We suggest the following troubleshooting approaches.

Client cannot connect to server

If you are using SSL or server certificates, first remove this complexity while you troubleshoot the connection issue. Then add SSL or server certificates back when you have found a solution. For more information, go to Configure Security Options for Connections in the Amazon Redshift Management Guide.

Connection is refused

Generally, when you receive an error message indicating that there is a failure to establish a connection, it means that there is an issue with the permission to access the cluster. For more information, go to The connection is refused or fails in the Amazon Redshift Management Guide.