Forum Discussion
OLE DB or ODBC error: [Expression Error] How to resolve this error.
It’s hard to know exactly what is causing this without a lot more info but the cause is either one (or a combination) of these:
- Complex Power Query transformations
- Complex data model (bi-directional relationships etc.)
- Complex DAX used in measures or calculated columns
- Dynamic M parameters
In general I feel like these things don’t pop up if you are limiting any transformations in Power Query and you follow Roche’s Maxim
Please mark this post as a solution if it helps you. Appreciate Kudos.
Hi sb53 ,
Thank you for the additional information. Since you are using a straightforward SELECT * query with no transformations or DAX, and the issue arises primarily when combining two tables with a many-to-one relationship, the error is likely related to how Power BI internally generates and folds queries when handling multiple tables.
I recommend first verifying that your relationship settings especially cardinality and cross-filter direction are correctly configured. Next, test by creating a simple visual that uses fields from both tables without any filters or measures to see if the error persists. It’s also important to ensure your data connector and drivers are up to date, as some limitations in connectors can cause folding failures.
Additionally, disabling the Auto Date/Time feature in Power BI options has resolved similar issues for others. To further isolate the cause, try loading the tables without establishing relationships and check if the error still occurs. Finally, if you are using DirectQuery mode, consider switching to Import mode to bypass query folding constraints. These steps should help identify and resolve the underlying issue.
If this post helps, then please consider to Accept as the solution to help the other members find it more quickly and a kudos would be appreciated.
Thank you.
Hi sb53 ,
I wanted to check if you had the opportunity to review the information provided. Please feel free to contact us if you have any further questions. If my response has addressed your query, please accept it as a solution and give a 'Kudos' so other members can easily find it.
Thank you.