What causes DF-Excel-DifferentSchemaNotSupport?

A wildcard path or folder scan picks up Excel files with different column headers or column counts. Monthly or versioned Excel reports were added to the folder with a structure that differs from earlier files. Some files have extra columns, merged header rows, or differently ordered columns compared to the baseline schema

How do I fix DF-Excel-DifferentSchemaNotSupport?

In the Excel source dataset, check whether a wildcard path or folder scan is configured.. List all files matching the wildcard and compare their first-row headers to identify schema-inconsistent files.. Move schema-inconsistent files to a separate folder, or split the data flow into separate source transformations per schema variant.. If all files should share the same schema, fix the source Excel files so their headers and column order match.. Enable Debug mode, run a data preview on the Excel source, and confirm all sampled rows come from files with a consistent schema.

Medium severitydata flow

Power BI Refresh Error:
DF-Excel-DifferentSchemaNotSupport

What does this error mean?

The ADF Mapping Data Flow Excel source is reading from multiple Excel files via a wildcard or folder path, but those files have different column schemas. The Excel connector requires all files in a batch read to share an identical column structure.

Common causes

1A wildcard path or folder scan picks up Excel files with different column headers or column counts
2Monthly or versioned Excel reports were added to the folder with a structure that differs from earlier files
3Some files have extra columns, merged header rows, or differently ordered columns compared to the baseline schema

How to fix it

1In the Excel source dataset, check whether a wildcard path or folder scan is configured.
2List all files matching the wildcard and compare their first-row headers to identify schema-inconsistent files.
3Move schema-inconsistent files to a separate folder, or split the data flow into separate source transformations per schema variant.
4If all files should share the same schema, fix the source Excel files so their headers and column order match.
5Enable Debug mode, run a data preview on the Excel source, and confirm all sampled rows come from files with a consistent schema.

Frequently asked questions

Does schema drift help with mismatched Excel files?

No — DifferentSchemaNotSupport is raised before schema drift can apply. The fundamental column layout must match across all files in the batch.

Can I use a Union transformation to merge Excel files with different schemas?

Yes — configure separate Excel source transformations for each schema variant, then use a Union with 'Allow schema drift' to combine them downstream.

How do I find which specific file is causing the schema mismatch?

Change the source to a specific file and run a Debug preview. Cycle through files to find the one whose schema differs from the others.

Official documentation: https://learn.microsoft.com/en-us/azure/data-factory/data-flow-troubleshoot-guide