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Medium severitydata source

Power BI Refresh Error:
DelimitedTextMoreColumnsThanDefined

What does this error mean?

ADF encountered more columns in the source file than defined in the dataset schema. The delimited text file has more columns than expected.

Common causes

  • 1The source delimited text file has more columns than the dataset schema declares
  • 2A schema change in the source file was not reflected in the ADF dataset
  • 3The wrong delimiter is configured, causing columns to be parsed incorrectly

How to fix it

  1. 1Open the dataset in ADF Studio and update the schema to match the actual file columns.
  2. 2Enable schema auto-detect on the dataset to infer the schema from the file.
  3. 3Review the source file to confirm the column count and delimiter settings.
  4. 4If the extra columns should be ignored, enable the fault tolerance option to skip incompatible rows.

Frequently asked questions

Does this error affect all pipeline runs or just the current one?

Depends on the root cause. A persistent misconfiguration fails every run; a transient issue may resolve on retry. Check the run history.

Can this error appear in Azure Data Factory and Microsoft Fabric pipelines?

Yes — the same connector errors appear in both ADF and Fabric Data Factory pipelines.

How do I see the full error detail for an ADF pipeline failure?

In ADF Monitor, click the failed run, then the failed activity. The detail pane shows the error code, message, and sub-error codes.

Will downstream Power BI datasets be affected when an ADF pipeline fails?

Yes — a dataset refreshing after the pipeline will use stale data or fail if the target table was cleared. The Power BI refresh may succeed while serving wrong data.

Official documentation: https://learn.microsoft.com/en-us/azure/data-factory/copy-activity-fault-tolerance

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