What causes Snowflake Schema Evolution Conflict?

New column in the source file has the same name but a different type than an existing column. Schema evolution would exceed the maximum number of columns (1000) for the target table. New column name conflicts with an existing column in a case-insensitive comparison. Source file drops a NOT NULL column that exists in the target table. ENABLE_SCHEMA_EVOLUTION is enabled but the file format is not Parquet or ORC (schema evolution only supported for semi-structured formats)

How do I fix Snowflake Schema Evolution Conflict?

Review the schema change in the incoming file and compare with the target table schema. For type conflicts, manually ALTER COLUMN to the wider type before re-running the load. If the column count approaches 1000, normalise the table structure or use a VARIANT column for dynamic attributes. For NOT NULL column drops, either make the column NULLable or ensure the source always provides it. Validate schema evolution is only used with Parquet, ORC, or JSON file formats

High severitydata loading

Power BI Refresh Error:
Snowflake Schema Evolution Conflict

What does this error mean?

A COPY INTO or Snowpipe load with ENABLE_SCHEMA_EVOLUTION=TRUE failed because the incoming file's schema change conflicts with existing table constraints, column types, or evolution limits.

Common causes

1New column in the source file has the same name but a different type than an existing column
2Schema evolution would exceed the maximum number of columns (1000) for the target table
3New column name conflicts with an existing column in a case-insensitive comparison
4Source file drops a NOT NULL column that exists in the target table
5ENABLE_SCHEMA_EVOLUTION is enabled but the file format is not Parquet or ORC (schema evolution only supported for semi-structured formats)

How to fix it

1Review the schema change in the incoming file and compare with the target table schema
2For type conflicts, manually ALTER COLUMN to the wider type before re-running the load
3If the column count approaches 1000, normalise the table structure or use a VARIANT column for dynamic attributes
4For NOT NULL column drops, either make the column NULLable or ensure the source always provides it
5Validate schema evolution is only used with Parquet, ORC, or JSON file formats

Frequently asked questions

Does ENABLE_SCHEMA_EVOLUTION work with all file formats?

No — schema evolution is supported for Parquet, ORC, Avro, and JSON formats. CSV files do not carry schema metadata so evolution is not supported for them.