What causes DF-Executor-InvalidPartitionFileNames?

A dynamic file name expression in the sink settings evaluates to null or an empty string — for example, a pipeline parameter that was not passed is used in the file name. The file name expression produces special characters that Azure storage does not allow in blob or ADLS file names. A date/time expression in the file name uses a format that produces characters like colons ('2024-01-15T10:30:00' contains a colon which is invalid in file names). The combination of container path + folder path + file name exceeds 1024 characters (Azure ADLS path length limit)

How do I fix DF-Executor-InvalidPartitionFileNames?

Open the failing sink transformation in ADF Studio and review the file name expression in the sink Settings tab.. Remove or fix any wildcard characters, path separators, or reserved characters from the file name pattern.. If using dynamic expressions for file names, test the expression in the expression builder to verify it produces a valid file name at runtime.. Switch the sink file naming from a custom expression to 'Output to single file' or a fixed pattern to eliminate dynamic naming issues.. Enable debug mode to execute the sink with a small data sample and verify the generated file names are valid for the target storage.

Medium severitydata flow

Power BI Refresh Error:
DF-Executor-InvalidPartitionFileNames

What does this error mean?

The sink is configured to generate partition file names using an expression or pattern that produces an invalid file name. The generated file name contains characters not allowed in Azure storage (e.g., /, \, :, *, ?, ", <, >, |), exceeds the maximum path length, or the expression evaluates to null or an empty string.

Common causes

1A dynamic file name expression in the sink settings evaluates to null or an empty string — for example, a pipeline parameter that was not passed is used in the file name
2The file name expression produces special characters that Azure storage does not allow in blob or ADLS file names
3A date/time expression in the file name uses a format that produces characters like colons ('2024-01-15T10:30:00' contains a colon which is invalid in file names)
4The combination of container path + folder path + file name exceeds 1024 characters (Azure ADLS path length limit)

How to fix it

1Open the failing sink transformation in ADF Studio and review the file name expression in the sink Settings tab.
2Remove or fix any wildcard characters, path separators, or reserved characters from the file name pattern.
3If using dynamic expressions for file names, test the expression in the expression builder to verify it produces a valid file name at runtime.
4Switch the sink file naming from a custom expression to 'Output to single file' or a fixed pattern to eliminate dynamic naming issues.
5Enable debug mode to execute the sink with a small data sample and verify the generated file names are valid for the target storage.

Frequently asked questions

What characters are not allowed in Azure Blob/ADLS file names?

Avoid these characters in Azure storage paths: \ : * ? " < > | (pipe). Spaces are allowed but cause URL and tooling issues — use only letters, numbers, hyphens, and underscores for safe file names.

How do I format a timestamp safely for use in a file name?

Use formatDateTime(utcNow(), 'yyyyMMdd_HHmmss') — ISO 8601's 'T' and colons are invalid in file names. Underscores produce safe, sortable timestamps.

How do I test what my file name expression evaluates to?

Click the expression icon on the file name field and use Preview to evaluate. Also add a Set Variable before the data flow to log the resolved value.

Will downstream Power BI datasets be affected?

Yes — the pipeline fails and the target storage path receives no new file. Dependent datasets serve stale figures.

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