SQL EndPoint - Successfuly connected but error during pre-login handshake (Error 10054)

[demerch1]

Dear all,

I created a warehouse , getting data through VNET from a SQL server located in a VM.. so far all was fine. Then I copied the SQL End point and tried to connect from SSMS where I received the following message:

"""
A connection was successfully established with the server, but then an error occurred during the pre-login handshake. (provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.) (Microsoft SQL Server, Error: 10054)

"""

how can I solve this ? any thoughts? 

thank you

[demerch1]

Hi again,, sorry for my late response,, I had to try several things to get to the conclusion. It was a client side issue (meaning my part) as I have to connect through Zscaler. When I disabled it , the connection worked.. so now we know.. Thank you for the support !!!

[v-nikhilan-msft · Accepted solution]

Hi @demerch1 
Thanks for using Fabric Community.
This error usually indicates an issue with the pre-login handshake, which establishes secure communication between the client (SSMS) and the server (Azure SQL Database) before authentication.

Troubleshooting Steps:

1. Verify TLS Compatibility:

   • Ensure both SSMS and Azure SQL Database support TLS 1.2 or higher. Disable lower versions on the client if necessary.
   • Check if your client application or driver has specific TLS requirements.

2. Check Network Configuration:

   • Validate that necessary TCP ports (1433 for standard communication, 5443 for encrypted) are open in all firewalls and security groups along the connection path.
   • Confirm VNET peering is correctly configured to allow communication between your SSMS subnet and the Azure SQL Database subnet.
   • Verify network ACLs don't restrict inbound connections to the database server.

3. Confirm Authentication Credentials:

   • Double-check that you're using the correct username, password, and server name in SSMS.
   • If using AAD authentication, ensure your Azure account has the necessary permissions and the SPN is correctly registered.

4. Address Azure SQL Database Configuration:

   • Remote connections should be enabled on the database server.
   • The user you're connecting with should have appropriate permissions to access the database.
   • Check if antivirus software or other security tools might be interfering with connections.
5. Disable firewall/VPN:  Disable firewalls or security groups for testing purposes to isolate the issue.
   

For more information please refer to this document here:
https://learn.microsoft.com/en-us/troubleshoot/sql/database-engine/connect/tls-exist-connection-clos...

Hope this helps. Please let me know if you have any further questions.

[v-nikhilan-msft]

Hi @demerch1 
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. Otherwise, will respond back with the more details and we will try to help.
Thanks