Forum Discussion
Helper IConnection error while using dataflow in power bi desktop
Hello experts,
When I try to connect the dataflow in desktop,it shows below error, would you pls advise me how to solve it?
Hi MostVIP2023,
This looks more like a SQL Server connection issue than a Dataflow issue.
The error says that the connection to SQL Server is established, but it fails during the pre-login handshake. In most cases, I would check the SQL Server connection, TLS/encryption settings, or network/firewall first.
I would try this:
First, connect to the same SQL Server directly from Power BI Desktop using Get Data > SQL Server. If you get the same error there, the Dataflow isn't the cause.
If the direct connection works, then check how the Dataflow is connecting to SQL Server, especially if an on-premises gateway is involved. In that case, test the connection from the gateway machine as well.
Also check whether there were any recent changes to:
- SQL Server or its TLS/encryption configuration
- Power BI Desktop
- SQL Server/ODBC drivers
- VPN, firewall or network security settings
The fact that the TCP connection succeeds but the pre-login handshake fails usually points towards TLS/encryption or something on the network interfering with the connection.
I would start with the direct SQL Server connection from Power BI Desktop. That will quickly tell you whether the problem is with SQL Server connectivity or specifically with the Dataflow/gateway setup.
5 Replies
- ShahRukhSameer
Solution Sage
Hi MostVIP2023,
This looks more like a SQL Server connection issue than a Dataflow issue.
The error says that the connection to SQL Server is established, but it fails during the pre-login handshake. In most cases, I would check the SQL Server connection, TLS/encryption settings, or network/firewall first.
I would try this:
First, connect to the same SQL Server directly from Power BI Desktop using Get Data > SQL Server. If you get the same error there, the Dataflow isn't the cause.
If the direct connection works, then check how the Dataflow is connecting to SQL Server, especially if an on-premises gateway is involved. In that case, test the connection from the gateway machine as well.
Also check whether there were any recent changes to:
- SQL Server or its TLS/encryption configuration
- Power BI Desktop
- SQL Server/ODBC drivers
- VPN, firewall or network security settings
The fact that the TCP connection succeeds but the pre-login handshake fails usually points towards TLS/encryption or something on the network interfering with the connection.
I would start with the direct SQL Server connection from Power BI Desktop. That will quickly tell you whether the problem is with SQL Server connectivity or specifically with the Dataflow/gateway setup.
- krishnakanth240
Super User
Hi MostVIP2023
It might be network level SQL pre-login timeout. Try toggling "Encrypt connection" setting in connector dialog then test same server from SSMS on same machine to confirm whether it is Power BI or network wide. If it is network then check your VPN stability, and temporarily disable firewall to see if SSL inspection is interrupting. Also confirm with your DBA that server is not hitting connection limits under load
RossEdwardsRioResolver I
Double check what authentication you are using to connect to the dataflow. Make sure you are using OAuth2 and not "windows".
Next thing to check after that is whether your firewall policy at your organisation requires a whitelisting to make a connection from your computer to Power BI. I've encountered that in the past and that is the error you get when the firewall is blocking your connection attempts.
- v-csrikanth
Community Support
Hi MostVIP2023
We would like to inquire whether have you got the chance to check the solutions provided by other users in community to resolve the issue. We hope the information provided helps to clear the query. Should you have any further queries, kindly feel free to contact the Microsoft Fabric community.
- v-csrikanth
Hi MostVIP2023
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. And, if you have any further query do let us know.
Thank you.
