What causes DF-Executor-illegalArgument?

A function was called with an argument of the wrong type — for example, passing a string column to a numeric function like floor() or round(). A window or aggregate function received an invalid parameter — for example, a negative window size or an empty partition specification. A pipeline parameter passed to the data flow has an invalid value — for example, a date parameter with a value that doesn't parse, passed to a date function. A regex function (rlike, regexMatch) received an invalid regular expression pattern string

How do I fix DF-Executor-illegalArgument?

Read the full error message in the ADF activity run output — it names the transformation function and the invalid argument value.. Open the failing Derived Column or expression in the ADF data flow expression builder and check the function arguments match the expected types.. If an argument is a pipeline parameter, verify the parameter value being passed is within the valid range for that function.. Enable debug mode and run the data flow interactively to step through each transformation and identify the exact expression raising the illegal argument.. Check the ADF expression language documentation for the specific function to confirm valid argument types and ranges.

Medium severitydata flow

Power BI Refresh Error:
DF-Executor-illegalArgument

What does this error mean?

A data flow expression function received an argument of an invalid type or an out-of-range value.

Common causes

1A function was called with an argument of the wrong type — for example, passing a string column to a numeric function like floor() or round()
2A window or aggregate function received an invalid parameter — for example, a negative window size or an empty partition specification
3A pipeline parameter passed to the data flow has an invalid value — for example, a date parameter with a value that doesn't parse, passed to a date function
4A regex function (rlike, regexMatch) received an invalid regular expression pattern string

How to fix it

1Read the full error message in the ADF activity run output — it names the transformation function and the invalid argument value.
2Open the failing Derived Column or expression in the ADF data flow expression builder and check the function arguments match the expected types.
3If an argument is a pipeline parameter, verify the parameter value being passed is within the valid range for that function.
4Enable debug mode and run the data flow interactively to step through each transformation and identify the exact expression raising the illegal argument.
5Check the ADF expression language documentation for the specific function to confirm valid argument types and ranges.

Frequently asked questions

How do I find which expression is causing the illegal argument error?

The error message includes the function name and rejected argument value. Search for that function in Derived Column, Filter, and aggregate transformations. The expression builder highlights the failing call with its built-in validator.

Can a pipeline parameter cause an IllegalArgument error in a data flow?

Yes — if a pipeline parameter resolves to an invalid value at runtime (e.g., empty string where a non-empty pattern is required), the function throws IllegalArgumentException. Test with 'Override parameters' in debug mode first.

How is this different from ExpressionParseError or Conversion?

ExpressionParseError: syntax error — expression can't be parsed. Conversion: type mismatch when casting. IllegalArgument: syntax and types are correct, but the value is invalid for the function (e.g., a negative number where positive is required).

Will downstream Power BI datasets be affected?

Yes — the pipeline fails and the target table receives no new data. Dependent datasets serve stale figures.

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