What causes DelimitedTextColumnNameNotAllowNull?

The CSV file's header row contains empty columns (two consecutive delimiters with nothing between them). Trailing delimiters on the header row create phantom empty columns. The header row contains only whitespace for one or more column names

How do I fix DelimitedTextColumnNameNotAllowNull?

Open the CSV file and inspect the header row for empty or whitespace-only column names.. Remove trailing delimiters at the end of the header row.. Assign meaningful names to all header columns, or use the "First row as header" option with a schema that maps columns by position instead of name.. Use a data flow transformation to filter out null column names after reading the file.

Medium severitydata source

Power BI Refresh Error:
DelimitedTextColumnNameNotAllowNull

What does this error mean?

An ADF copy activity encountered a null or empty column name in the CSV header row. ADF requires all columns to have non-empty names when the first row is the header.

Common causes

1The CSV file's header row contains empty columns (two consecutive delimiters with nothing between them)
2Trailing delimiters on the header row create phantom empty columns
3The header row contains only whitespace for one or more column names

How to fix it

1Open the CSV file and inspect the header row for empty or whitespace-only column names.
2Remove trailing delimiters at the end of the header row.
3Assign meaningful names to all header columns, or use the "First row as header" option with a schema that maps columns by position instead of name.
4Use a data flow transformation to filter out null column names after reading the file.

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/connector-troubleshoot-delimited-text