Dataflow Gen2 Error message: Unexpected error occurred while creating your data destination

[JK_CM]

I'm having issues with refreshing a dataflow gen2. It gives the Error code: 101238, of which I can't find any documentation. It seems to suggest that the datatypes are not correct. However, I've tried refreshing it with a simple table containing all text columns and I still get the same error message. 

Is it possible the source (AFAS) has something to do with it? I can query the data in the dataflow just fine. It's really the writing to the lakehouse (I've also tried Warehouse as a destination) that doesn't work.

I've created another dataflow with SQL as a source and that has not had any issues. 

[v-agajavelly]

Hi @JK_CM ,

Just checking in were you able to raise a support ticket with Microsoft regarding the Gen2 write issue? If so, would be great to hear if they shared any updates or workaround.

Regards,
Akhil.

[JK_CM]

Unfortunately not, since I don't have the (admin) rights to do in this environment

[v-agajavelly]

Hi @JK_CM 

Totally get that, when something so simple won’t go through. And yes, it’s odd that even a tiny table with all text fields fails. Good to hear notebooks are working as a workaround but agreed, it’s not as convenient as dataflows for quick transformations. This might be a backend bug with the Gen2 writer. Might be worth logging a support ticket with Microsoft, especially since Gen1 works fine and it’s clearly not a data issue. I’d recommend raising a support ticket with Microsoft so it’s officially logged and can help influence future improvements. You can do that here. https://learn.microsoft.com/en-us/power-bi/support/create-support-ticket

Regards,
Akhil.

[v-agajavelly]

Hi @JK_CM 

Thanks for confirming it's a REST API. Since Gen1 works fine, the issue is likely with how Gen2 handles writing to the Lakehouse or Warehouse.

A few quick things to check.

• Make sure all column names are clean (no special characters or duplicates).
• Try manually setting data types instead of relying on auto-detection.
• Test writing to a brand new Lakehouse or Warehouse to rule out schema conflicts.
• Also try switching between append and replace as the load method.

Gen2 can be a bit sensitive with schema mapping, especially during write operations.

Let us know if any of these help.
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Best regards,
Akhil.

[JK_CM]

I've tried this with a single table containing 9 rows and three text columns and am still getting the same error. I've switched to a notebook, which seems to work. It's very unfortunate, because I really like working with dataflows. 

[JK_CM]

No, I'm using a REST API. When I use a dataflow Gen1, I'm not having any issues. 

[nilendraFabric]

Hi @JK_CM 

by any chance the data source in your case is on prem and u are using data gateway 

Error 101238 in Dataflow Gen2 typically occurs when writing data to a Lakehouse or Warehouse destination, often linked to connectivity issues, gateway configurations,