Source data has missing values for required fields. ETL transformation produces NULL for a column that previously had values. Schema migration added a NOT NULL constraint without providing default values. JOIN producing NULL for non-nullable columns due to unmatched rows

Step 1: Identify the column from the error: `ERROR: null value in column 'X' violates not-null constraint`.. Step 2: Add COALESCE() or a default value in the transformation: `COALESCE(source_col, 'default')`.. Step 3: Audit source data for rows where the required field is missing.. Step 4: If appropriate, alter the column to allow NULLs: `ALTER TABLE t ALTER COLUMN c DROP NOT NULL;`.

High severitydata format

Power BI Refresh Error:
23502

What does this error mean?

An INSERT or UPDATE attempted to store NULL in a column defined as NOT NULL.

Common causes

1Source data has missing values for required fields
2ETL transformation produces NULL for a column that previously had values
3Schema migration added a NOT NULL constraint without providing default values
4JOIN producing NULL for non-nullable columns due to unmatched rows

How to fix it

1Step 1: Identify the column from the error: `ERROR: null value in column 'X' violates not-null constraint`.
2Step 2: Add COALESCE() or a default value in the transformation: `COALESCE(source_col, 'default')`.
3Step 3: Audit source data for rows where the required field is missing.
4Step 4: If appropriate, alter the column to allow NULLs: `ALTER TABLE t ALTER COLUMN c DROP NOT NULL;`.

Frequently asked questions

How do I prevent 23502 errors in automated pipelines?

Add retry logic with exponential backoff, validate data quality before loading, and monitor pipeline failures in MetricSign to catch this error early.

Official documentation: https://www.postgresql.org/docs/current/errcodes-appendix.html