SQL Server JDBC “unexpected pre-login response” error in Foundry Data Connection

Ask the Community
1

We’re encountering a SQL Server connection failure when configuring a Foundry SQL Data Connection.

Error observed (Explorer / Magritte):

java.lang.Throwable: RemoteException: INVALID_ARGUMENT (MagritteExplorer:SqlError)
Error: The driver received an unexpected pre-login response while connecting to SQL Server.

Context:

  • Database: Microsoft SQL Server

  • Connection path: Foundry Data Connection (Explorer / Magritte)

  • Endpoint: public SQL Server endpoint

  • Authentication and credentials are valid

  • SQL Server version is 2005+

Validation performed:

  • SQL Server is running and accessible from other clients

  • The expected TCP port is open

  • From the Palantir environment, a netcat test to the public SQL Server endpoint and port succeeds, confirming TCP connectivity and egress

  • The failure occurs during the JDBC pre-login handshake, after TCP connection succeeds