Power BI API Parameters error - ActionNotSupported

This looks like a real Update Parameters API limitation rather than a simple “parameter not found” problem.

The GET output confirms Power BI can see the parameters, so I would focus on whether the semantic model itself is supported by Default.UpdateParameters.

Microsoft currently documents these important limitations:

• semantic models created or modified through the public XMLA endpoint are not supported by this API
• DirectQuery is supported only with enhanced dataset metadata
• Azure Analysis Services live connections are not supported
• parameter names are case-sensitive
• Any and Binary parameter types cannot be updated Microsoft Learn

Since the error points specifically to parameter position 3, I would test the update request with only the first two parameters, then add the third one back separately. That should help identify whether EntityID itself is unsupported or whether something in the query that consumes that parameter makes the action unsupported.

Also check whether this report/semantic model was ever modified through XMLA or uses DirectQuery without enhanced metadata, because either can cause this API to fail even when GET still returns the parameter list. 

So I’d test in this order:

1. Update only Server and Database.
2. Update only EntityID.
3. Verify the semantic model was not modified via XMLA.
4. If using DirectQuery, confirm enhanced dataset metadata is enabled.
5. Compare the Power Query usage of EntityID with one of the parameters that updates successfully.

The ActionNotSupported message usually points more toward the semantic model/query configuration than the parameter simply being text or load-enabled.