OLE DB or ODBC error: [Expression Error] How to resolve this error.

[sb53]

I am getting this error on 1 sheet of the visulaization. OLE DB or ODBC error: [Expression Error] We couldn't fold the expression to the data source. Please try a simpler expression. Somebody help me to resolve this query.

[v-tsaipranay]

Hi @sb53 ,

May I ask if you have resolved this issue? If so, please mark the helpful reply and accept it as the solution. This will be helpful for other community members who have similar problems to solve it faster.

Thank you.

[v-tsaipranay]

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.

[v-tsaipranay]

Hi @sb53 ,

Thank you for reaching out to the Microsoft Fabric community forum. Also, thanks to @andrewsommer  for the response.

The error you're encountering "We couldn't fold the expression to the data source" typically means that one or more steps in your Power Query transformation are too complex or unsupported for the connector you're using, preventing query folding.

To resolve this, open Power Query Editor and review each step by right-clicking and selecting "View Native Query". When this option is greyed out, folding has already broken at or before that step.

Try simplifying or removing non-foldable steps such as custom columns with complex logic, Table.Buffer, or conditional expressions like try...otherwise. Where possible, shift such logic to DAX or your source system (e.g., SQL).

If needed, consider splitting your query into two: one that loads raw data with foldable logic, and another that applies additional transformations.

Hope this helps. Please reach out for further assistance.

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.

[sb53]

Hi, we are using simplist query that is [ select * from tablename], no dax query, no applied steps. Then also we are facing this issue, majorly we are facing this issue when we try to use data from 2 tables, they have many to one relationship,  same data also, same datatype. Then also same issue.

[v-tsaipranay]

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.

[v-tsaipranay]

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.

[sergej_og]

Where does this message appear - Desktop or Service?
Did it worked before?

[andrewsommer · Accepted solution]

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.