Unsolveable Mashup Data Access Error

Hi regnidem16 

Thank you for contacting the Microsoft Fabric Community Forum.

The DM_GWPipeline_Gateway_MashupDataAccessError arises in Power BI Service due to strict data privacy enforcement when combining data from multiple sources, especially involving external web APIs. In this scenario, the issue is linked to the Revenue Segment - Load query, which contains steps still being dynamically evaluated during a merge in another query. This behavior conflicts with the mashup engine’s privacy model, even if intermediate buffering is applied.

To address this, ensure that the final output of the Revenue Segment - Load query is explicitly buffered before being referenced elsewhere. This can be achieved by wrapping the final step with Table.Buffer() and assigning it to a variable (e.g., BufferedFinal = Table.Buffer(#"Renamed Columns")), then returning this variable. This approach fully materializes the API data prior to any merge operations, preventing re-evaluation at refresh time.

Regards,
Karpurapu D,
Microsoft Fabric Community Support Team.