Forum Discussion
Translytical task flow — Viewer role cannot trigger data function button, Member role works
Thank you for your responses. I have contacted Micorosft Suppoert and with their help I was able to solve the permission issues. The following has to be applied:
For a Viewer to successfully perform a writeback via a User Data Function, the following access must be granted in addition to report access:
- Consumers must be added as Viewers to the workspace(s) where the report resides, and to the workspace(s) where the database and the User Data Function reside (if different).
- They need Build permission at item level on the semantic model.
- They need Read, Write and Execute permissions at item level on the User Data Function.
- They need Read and ReadData permissions at item level on the DWH (Data Warehouse) where the writeback tables are located.
Super UserHi! The "Refresh the report automatically" option on the button likely write-back permission on the semantic model, which Viewers don't have. In Power BI, triggering a semantic model refresh programmatically — even a report-level refresh initiated by a button — goes through the same permission gate as the XMLA write endpoint. Viewers are explicitly excluded from this.
This means even if your UDF executes successfully, the subsequent refresh call fails, and Power BI likely rolls the whole operation back or reports the composite action as failed. Turn off "Refresh the report automatically" first and test whether the Viewer can execute the write-back cleanly. If they can, you've confirmed this is the failure point.
What does a report-side consumer actually need?
This is poorly documented, but based on the Member vs Viewer behavior you're seeing, the likely minimum is Contributor on the report workspace, not just Viewer. Here's why:
- Viewer is a consumption-only role. It grants read access to reports and datasets but explicitly blocks any action that writes to or modifies workspace items — including triggering dataset refreshes.
- The data function button in a translytical flow is not a pure "read" action from Power BI's perspective. Even though the write goes to Workspace A, the button invocation is brokered through the report/semantic model layer in Workspace B, and that brokering apparently requires more than Viewer rights.
- Member adds the ability to interact with workspace content in write-adjacent ways, which is why it unblocks the flow.
Recommended path forward
- Disable "Refresh the report automatically" and retest with a Viewer — this isolates whether refresh permission is the failure point.
- If write-back succeeds without auto-refresh, implement a workaround: use a Power Automate flow triggered by the UDF completion to handle the refresh, since flows run under their own credentials rather than the end user's workspace permissions.
- If write-back still fails without auto-refresh, the report workspace role itself is gating UDF invocation, and you'll need to either raise affected users to Contributor or restructure so the report lives in the Fabric workspace (Workspace A) alongside the UDF.
- File a support ticket with Microsoft specifically asking for documentation on minimum report-workspace permissions for translytical task flow consumers — this gap in the docs is real and worth getting a written answer on