MDX session-scope statements like CREATE MEMBER are not allowed on DirectLake models

[dbeavon3]

I have a pretty simple semantic model with one table pointed at DirectLake (DL on OL).

Most of my tables are "import" tables for the sake of a high-quality pivot table experience in Excel.

When I build pivot tables, I have no problems until I try to create custom calcs or sets.  The Excel U/I allows me to try to create a new calc, and even gives me positive feedback from the "test" button (below) ...

... but when I try to click the OK button I get a real ugly message:

MDX session-scope statements like CREATE MEMBER are not allowed on DirectLake models

As near as I can tell this is the first posting about the error message on the entire internet.  Either people don't use Excel pivot tables very often, or they aren't building semantic models using the new "DirectLake on OneLake" (I think this variety of semantic model is still in "public preview").

Does anyone have a good workaround for allowing users to build their own calculations?  My only recommendation is for them to use power query and ingest everything they need into a local Data Model in Excel.  After doint that, I think they will have no more restrictions when it comes to creating calculations.  Any other tips would be appreciated.

[v-pnaroju-msft]

Hi dbeavon3,

We would like to follow up and check whether the details we shared have helped to resolve your problem.
If you need any more assistance, please feel free to connect with the Microsoft Fabric community.

Thank you.

[v-pnaroju-msft]

Hi dbeavon3,

Thank you for your inquiry via the Microsoft Fabric Community Forum.

Based on my understanding, the error indicating that MDX session scoped statements such as CREATE MEMBER are not allowed on Direct Lake models arises because Direct Lake semantic models do not permit session scoped MDX statements (for example, CREATE MEMBER, CREATE SET, etc.). Excel’s Create Calculation or Calculated Member feature issues exactly these session MDX statements, which causes the operation to fail. Microsoft’s Direct Lake documentation explicitly states that session scoped MDX is disallowed, although query scoped MDX WITH clauses remain supported.

Please follow a workaround as below:

1. Add the calculation into the semantic model itself using Power BI Desktop or Fabric by authoring the calculation in DAX. This ensures Excel users see the calculation as a built-in measure, eliminating the need for users to issue CREATE MEMBER statements at runtime and aligning with supported functionality.

For further details, please refer to the link below:
Direct Lake overview - Microsoft Fabric | Microsoft Learn

We hope the information provided helps to resolve the issue. If you have any further queries, please feel free to contact the Microsoft Fabric community.

Thank you.