What causes DELTA_UNRESOLVABLE_DATE_PARTITION?

The source data contains a date string in an unexpected format (e.g., `DD/MM/YYYY` instead of `YYYY-MM-DD`). A null or empty value was written to a date partition column. A date value is outside the valid Spark/Delta range (before year 0001 or after year 9999). The partition column type is DATE but the source data is a STRING with non-date content

How do I fix DELTA_UNRESOLVABLE_DATE_PARTITION?

Cast the partition column to DATE explicitly before writing: `CAST(date_col AS DATE)` to enforce format validation.. Filter out null or invalid date values upstream: `WHERE date_col IS NOT NULL AND date_col REGEXP '\d{4}-\d{2}-\d{2}'`.. If the source date format differs from ISO 8601, use `to_date(date_col, 'DD/MM/YYYY')` to parse it correctly.. Check the source data for sentinel values like `9999-12-31` or `0000-01-01` that may be outside the valid Delta range.

Medium severitysql

Power BI Refresh Error:
DELTA_UNRESOLVABLE_DATE_PARTITION

What does this error mean?

Delta Lake cannot resolve a date-based partition value. The partition column contains a date string that does not match the expected format or falls outside the valid date range.

Common causes

1The source data contains a date string in an unexpected format (e.g., `DD/MM/YYYY` instead of `YYYY-MM-DD`)
2A null or empty value was written to a date partition column
3A date value is outside the valid Spark/Delta range (before year 0001 or after year 9999)
4The partition column type is DATE but the source data is a STRING with non-date content

How to fix it

1Cast the partition column to DATE explicitly before writing: `CAST(date_col AS DATE)` to enforce format validation.
2Filter out null or invalid date values upstream: `WHERE date_col IS NOT NULL AND date_col REGEXP '\d{4}-\d{2}-\d{2}'`.
3If the source date format differs from ISO 8601, use `to_date(date_col, 'DD/MM/YYYY')` to parse it correctly.
4Check the source data for sentinel values like `9999-12-31` or `0000-01-01` that may be outside the valid Delta range.

Frequently asked questions

Can I write rows with null dates to a date-partitioned Delta table?

Delta allows a special `__HIVE_DEFAULT_PARTITION__` for nulls, but this requires explicit configuration. By default, nulls in a partition column cause errors — filter them out or use a default date value.