What causes DF-Executor-DSLParseError?

An expression uses reserved words or unsupported syntax that the ADF expression parser rejects — for example, SQL-style `CASE WHEN` instead of ADF's `iif()` function. A data flow was exported and re-imported between ADF environments, introducing subtle differences in expression encoding or escaping that the parser cannot handle. A complex nested expression has unbalanced parentheses or mismatched function argument counts that were not caught by the expression builder before publishing. A pipeline parameter reference uses ARM template syntax (`@pipeline().parameters.x`) in a data flow expression context instead of the data flow parameter syntax (`$paramName`)

How do I fix DF-Executor-DSLParseError?

Open the data flow in ADF Studio — the DSL parse error highlights the failing expression in the expression editor; look for red underlines or a validation warning banner.. Check all Derived Column, Filter, Conditional Split, and Join transformations for syntax errors — common mistakes include unmatched parentheses, missing function arguments, and using double-quoted strings (use single quotes for string literals in ADF expression language).. If the expression was recently edited using a pipeline parameter or dynamic expression, verify that the parameter value is a valid string that does not contain characters that break the expression syntax when interpolated.. Validate each expression using the 'Expression builder' in ADF Studio — click the expression field and use the built-in validator to check syntax.. If the data flow was recently imported or copied between environments, re-open each transformation's expression editor to force ADF Studio to re-validate the DSL — import can produce expression strings that differ slightly from what the executor expects.

Medium severitydata flow

Power BI Refresh Error:
DF-Executor-DSLParseError

What does this error mean?

ADF cannot parse the data flow's domain-specific expression language (DSL). A transformation expression — in a Derived Column, Filter, Join condition, or Aggregate — contains a syntax error that the ADF expression engine rejects before any data is processed.

Common causes

1An expression uses reserved words or unsupported syntax that the ADF expression parser rejects — for example, SQL-style `CASE WHEN` instead of ADF's `iif()` function
2A data flow was exported and re-imported between ADF environments, introducing subtle differences in expression encoding or escaping that the parser cannot handle
3A complex nested expression has unbalanced parentheses or mismatched function argument counts that were not caught by the expression builder before publishing
4A pipeline parameter reference uses ARM template syntax (`@pipeline().parameters.x`) in a data flow expression context instead of the data flow parameter syntax (`$paramName`)

How to fix it

1Open the data flow in ADF Studio — the DSL parse error highlights the failing expression in the expression editor; look for red underlines or a validation warning banner.
2Check all Derived Column, Filter, Conditional Split, and Join transformations for syntax errors — common mistakes include unmatched parentheses, missing function arguments, and using double-quoted strings (use single quotes for string literals in ADF expression language).
3If the expression was recently edited using a pipeline parameter or dynamic expression, verify that the parameter value is a valid string that does not contain characters that break the expression syntax when interpolated.
4Validate each expression using the 'Expression builder' in ADF Studio — click the expression field and use the built-in validator to check syntax.
5If the data flow was recently imported or copied between environments, re-open each transformation's expression editor to force ADF Studio to re-validate the DSL — import can produce expression strings that differ slightly from what the executor expects.

Frequently asked questions

How is DSLParseError different from ExpressionParseError?

DSLParseError is raised at the ADF DSL compiler level — the expression string cannot be parsed. ExpressionParseError is raised by the evaluator during execution. The fix is the same: find and correct the invalid expression syntax.

ADF Studio does not show any red underlines — why does the pipeline still fail?

ADF Studio validates syntax but doesn't catch all runtime parse issues — some surface only when the executor compiles the full DSL on the cluster. Re-open each expression editor and press 'Refresh'.

Can importing a pipeline from Git cause a DSLParseError?

Yes — Git-to-ADF round-trips can introduce encoding differences. Special characters (backticks, smart quotes, Unicode spaces) may be preserved in JSON but misinterpreted by the DSL parser. Re-open and re-save each expression in ADF Studio after importing from Git.

Will downstream Power BI datasets be affected?

Yes — the pipeline fails without processing any data. Dependent datasets and reports serve stale figures until the expression syntax is corrected.

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