Cannot connect to Fabric lakehouse SQL endpoint #461
Description
I am experiencing a RuntimeError: 0x2746 when attempting to connect to a Microsoft Fabric Lakehouse SQL Endpoint. Crucially, this error persists even when using the provided Dev Container environment, which should have all dependencies pre-configured.
https://github.com/microsoft/mssql-python/blob/main/.devcontainer/Dockerfile
https://github.com/microsoft/mssql-python/blob/main/.devcontainer/devcontainer.json
Environment
Mode: VS Code Dev Container (Docker)
Base Image: mcr.microsoft.com/devcontainers/python:3.14-bookworm
Library: mssql-python
Target Server: Microsoft Fabric Lakehouse SQL Endpoint
Diagnostic Evidence
- Verification of Network/TLS (from within the Container)
I ran an openssl test from the Dev Container terminal to ensure the container can reach the outside world and complete a TLS handshake:
$ openssl s_client -connect <endpoint>.datawarehouse.fabric.microsoft.com:1433
returns
SSL handshake has read 4539 bytes and written 2165 bytes
Verification: OK
Protocol: TLSv1.3
Verify return code: 0 (ok)
Note: The handshake succeeds even if Fabric capacity is paused, proving the network path is open.
- Steps to Reproduce
Despite the successful TLS handshake, the Python library fails during the connection phase:
import mssql_python
conn_str = (
f"SERVER=tcp:{<endpoint>.},1433;"
f"DATABASE={db};"
f"Authentication={auth_method};"
f"Encrypt=yes;"
)
conn = mssql_python.connect(conn_str)throws
RuntimeError: [Microsoft][ODBC Driver 18 for SQL Server]TCP Provider: Error code 0x2746
and
# ran az login prior to this
sqlcmd -S <endpoint>.datawarehouse.fabric.microsoft.com,1433 -d LakehouseName -G -C
returns
Sqlcmd: Error: Microsoft ODBC Driver 18 for SQL Server : TCP Provider: Error code 0x2746.
Sqlcmd: Error: Microsoft ODBC Driver 18 for SQL Server : Communication link failure.