Skip to main content
cancel
Showing results for 
Search instead for 
Did you mean: 

Did you hear? There's a new SQL AI Developer certification (DP-800). Start preparing now and be one of the first to get certified. Register now

Reply
clemlanoe
Regular Visitor

Dataflow Refresh Error with SharePoint

Hi,

 

I've had a data flow that is connected to a Sharepoint csv for months without issue and now I'm getting the following error when refreshing the data:

 

"SharePoint: Request failed: The underlying connection was closed: An unexpected error occurred on a send."

 

I've tried clearing the permissions and reconnected but end up with the same error.

 

I've also tried uninstalling and reinstalling Power Bi desktop.

 

[EDIT]

 

Upon further investigation, I found that it succesfully located my CSV file on SharePoint but then fails when retrieving the binary content with a slightly different error message:

 

"DataSource.Error: The underlying connection was closed: An unexpected error occurred on a send."

 

[EDIT 2.0]

 

I have managed to extract a more detailed error message:

 

Unexpected error: The underlying connection was closed: An unexpected error occurred on a send.
Details:

Microsoft.Mashup.Evaluator.Interface.ErrorException: The underlying connection was closed: An unexpected error occurred on a send. ---> Microsoft.Mashup.Evaluator.Interface.ErrorException: The underlying connection was closed: An unexpected error occurred on a send. ---> Microsoft.Mashup.Evaluator.Interface.ErrorException: The underlying connection was closed: An unexpected error occurred on a send. ---> Microsoft.Mashup.Evaluator.Interface.ErrorException: The underlying connection was closed: An unexpected error occurred on a send. ---> Microsoft.Mashup.Evaluator.Interface.ErrorException: The underlying connection was closed: An unexpected error occurred on a send. ---> Microsoft.Mashup.Engine1.Library.Http.ResponseException: The underlying connection was closed: An unexpected error occurred on a send. ---> Microsoft.Mashup.Engine1.Library.Http.ResponseException: The underlying connection was closed: An unexpected error occurred on a send. ---> System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a send. ---> System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. ---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host
at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)
--- End of inner exception stack trace ---

at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)
at System.Net.FixedSizeReader.ReadPacket(Byte[] buffer, Int32 offset, Int32 count)
at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.CheckCompletionBeforeNextReceive(ProtocolToken message, AsyncProtocolRequest asyncRequest)
at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest, Boolean renegotiation)
at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult)
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Net.TlsStream.ProcessAuthentication(LazyAsyncResult result)
at System.Net.TlsStream.Write(Byte[] buffer, Int32 offset, Int32 size)
at System.Net.PooledStream.Write(Byte[] buffer, Int32 offset, Int32 size)
at System.Net.ConnectStream.WriteHeaders(Boolean async)
--- End of inner exception stack trace ---

2 REPLIES 2
otravers
Community Champion
Community Champion

I'm a bit confused by your troubleshooting steps as you mentioned Power BI Desktop which is not used to set up dataflows. Where are you seeing the error, in the Power BI service? Then let's rule out Desktop to keep things simple.

 

Your detailed error message suggests some sort of networking error or blocking. Let's start from the beginning. Are you still able to browse your SharePoint library (using the same account used to authenticate in the dataflow) as well as download your CSV? How large is this CSV file?

------------------------------------------------
1. How to get your question answered quickly - good questions get good answers!
2. Learning how to fish > being spoon-fed without active thinking.
3. Please accept as a solution posts that resolve your questions.
------------------------------------------------
BI Blog: Datamarts | RLS/OLS | Dev Tools | Languages | Aggregations | XMLA/APIs | Field Parameters | Custom Visuals

Thank you for your detailed response. Apologies, I meant to post this under "Desktop" and not "Service".

 

I will do that now.

 

And yes, I am still able to browse my SharePoint library form within Power Bi.

Helpful resources

Announcements
April Power BI Update Carousel

Power BI Monthly Update - April 2026

Check out the April 2026 Power BI update to learn about new features.

Fabric SQL PBI Data Days

Data Days 2026 coming soon!

Sign up to receive a private message when registration opens and key events begin.

New to Fabric survey Carousel

New to Fabric Survey

If you have recently started exploring Fabric, we'd love to hear how it's going. Your feedback can help with product improvements.

Power BI DataViz World Championships carousel

Power BI DataViz World Championships - June 2026

A new Power BI DataViz World Championship is coming this June! Don't miss out on submitting your entry.