Power BI Refresh Error:
DF-Synapse-InvalidFormat

What does this error mean?

The data format or column format used in the Synapse Analytics sink or source is invalid for the operation.

Common causes

• 1A date or datetime column is formatted in a way that does not match the Synapse column type — for example, an ISO 8601 string written to a DATETIME2 column
• 2The staging file format settings in the data flow sink do not match what Synapse expects for COPY INTO
• 3A NULL value is being written to a NOT NULL column in the Synapse target table
• 4Special characters or line endings in string columns break the staging file delimiters
• 5A numeric string (e.g., '1,234.56') cannot be parsed to a DECIMAL column because of locale-specific formatting

How to fix it

1. 1Read the error detail in the ADF activity run output — it names the column and the value that failed to parse.
2. 2Enable debug mode in ADF Studio and run a Data Preview on the sink transformation to see which rows fail.
3. 3Check the column type mapping between the source data and the Synapse target table in the data flow's mapping tab — look for type mismatches on date, numeric, and string columns.
4. 4For date format mismatches: add a Derived Column transformation before the sink to cast the date to the correct format using toDate() or toTimestamp() with an explicit format string.
5. 5For numeric format mismatches: clean numeric strings using replace(columnName, ',', '') before casting to a numeric type.
6. 6Verify that NOT NULL columns in Synapse always receive a non-null value — use iifNull(columnName, defaultValue) in a Derived Column to handle NULLs.
7. 7If the problem is in the staging file format, check the data flow sink's format settings and ensure they match the COPY INTO format Synapse expects (Parquet or delimited text with correct column delimiters).

Frequently asked questions

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