Google Cloud SQL Proxy issue - tls: server selected unsupported protocol version 303

Question

I've been connecting to Google Cloud SQL Postgres Instance from the CloudSQL Proxy on Windows for years. All of a sudden, I'm unable to connect

When I start the proxy using Cloud SDK, it launches fine and says ready for new connections. Then when I try to connect to it on 127.0.0.1, the client throws error : couldn't connect to "instance": tls: server selected unsupported protocol version 303

My cloud run service is able to connect and even I am able to connect using cloud shell. I am facing this issue only while trying to connect using cloud sql proxy.

Any thoughts on this issue is much appreciated.

I tried to connect to Cloud sql postgres instance using Cloud sql proxy. I am getting below error after establishing the connection to instance and trying to connect to 127.0.0.1:5432 using dbeaver. couldn't connect to "instance": tls: server selected unsupported protocol version 303

Answer 1

I had the same symptoms on my PC, which is a SASE terminal (globalprotect + prismaaccess):

tls: server selected unsupported protocol version 303

After I DISABLE PaloAltoGlobalProtect, I can now connect to the CloudSQL Instance via CloudSQLProxy.

This seems to be caused by a configuration problem in my network environment (PaloAltoGlobalProtect or ParoAltoPrismaAccess).