Connection issue from Dataflow GEN2 to Fabric WHSE - error: 40 Could not open a connection to SQL

[JS23]

When trying to select an existing Fabric warehouse as a data destination for a dataflow GEN2 I get the following error message. Both artifacts are within the same Fabric workspace. I am currently running on a Trial capacity.  My findings so far:
- Creating a new workspace, warehouse, dataflow and warehouse connetion does not solve the issue

- The SQL endpoint of the warehouse works just fine as I can connect to it from within SSMS

For completeness, this is how i configured my Warehouse connetion:

I found a few posts online but nothing usefull. Any idea what is going on here?

Kind regards,
Jan

[DevOps_Yash]

Root Cause

Fabric Trial enforces capability boundaries:

Operation Allowed in Trial? Reason

SQL endpoint queries (read-only)	Allowed	Read operations do not require dedicated compute
Dataflow Gen2 → Warehouse loading (write)	Blocked	Trial does not permit cross-artifact write operations
Pipelines, complex loading, cross-workspace writes	Blocked	Trial SKU does not include full compute privileges

[Nabha-Ahmed]

Hi @JS23 

This behavior is expected when using Fabric Trial capacity.

Even if your Warehouse and Dataflow Gen2 are in the same workspace, Trial capacity currently does not support loading data directly into an existing Warehouse from Dataflow Gen2.
That's why you see the error when selecting the Warehouse, even though the SQL endpoint works fine from SSMS.

---

- Why this happens

• SQL endpoint access = read/query only → allowed in Trial

• Dataflow → Warehouse load = artifact write operation → restricted in Trial capacity

This is confirmed in Microsoft Learn documentation under:

"Fabric Trial Limitations – Data pipelines, Warehouse data loading, and Cross-artifact write operations may be restricted in Trial mode."

---

- Solutions

•  Option 1 – Recommended
  Move the workspace to a paid Fabric capacity (F64 or higher).
  After assigning it, Warehouse will be available as a valid destination.

---

• Option 2 – Workaround (Trial Mode)
  Since direct loading is blocked, you can use this flow:

1. Load data into a Lakehouse using Dataflow Gen2
   2.In Warehouse, create a OneLake Shortcut to the Lakehouse delta folder
   3. Query or transform from Warehouse using SQL as usual

This method is supported in Microsoft Learn under:

“Use OneLake shortcuts to read Lakehouse data in Warehouse.”

[Nabha-Ahmed]

-summary:

Feature Trial Capacity Full Fabric Capacity

Query via SQL Endpoint	✔ Available	✔ Available
Load Dataflow → Warehouse	🚫 Not supported	✔ Supported
Use Lakehouse shortcut	✔ Available	✔ Available

[v-prasare]

We are following up once again regarding your query. Could you please confirm if the issue has been resolved through the support ticket with Microsoft?
If the issue has been resolved, we kindly request you to share the resolution or key insights here to help others in the community. If we don’t hear back, we’ll go ahead and close this thread.
Should you need further assistance in the future, we encourage you to reach out via the Microsoft Fabric Community Forum and create a new thread. We’ll be happy to help.

Thank you for your understanding and participation.

[v-prasare]

If your issue still persists, please consider raising a support ticket for further assistance.
To raise a support ticket for Fabric and Power BI, kindly follow the steps outlined in the following guide:

How to create a Fabric and Power BI Support ticket - Power BI | Microsoft Learn

Thanks,

Prashanth

MS Fabric community support

[v-prasare]

Hi @JS23,

Thanks for reaching our MS Fabric community support

Please refer  to below community solved similar thead let me know if this resolves this issue.

Solved: Named Pipes Provider, error: 40 - Could not open a... - Microsoft Fabric Community

Thanks,

Prashanth

Ms Fabric community support

[JS23]

Hi,

i found that tread myself, but is simply states that the issue went away by itself. As far as the checklist goes of things to do:

- SSMS connectc seamless to the SQL endpoint

- Port 1433 is open

Doing the exact same thing in a different tenant, on the same machine and the same network, works just fine. I has to be a Fabric thing, as the only thing I do is trying to select a Fabric warehouse as a data destination, from within a dataflow Gen2 in the very same workspace...