What causes AMBIGUOUS_REFERENCE?

JOIN between two tables that both contain a column with the same name, referenced without a table qualifier. SELECT * used in a subquery or CTE, causing duplicate column names to propagate. Aliased expressions reusing the same name as source columns within the same SELECT list. LATERAL VIEW or EXPLODE producing a column name already present in the outer query. Nested structs accessed with a short field name that exists at multiple nesting levels

How do I fix AMBIGUOUS_REFERENCE?

Qualify the ambiguous column with its table or alias: `table_a.column_name` instead of just `column_name`. Replace SELECT * with explicit column lists, using aliases where names overlap. Rename conflicting columns with AS in the subquery or CTE before referencing them in the outer query. Run `DESCRIBE ` on all joined tables to identify overlapping column names before writing the query. Use backtick quoting for struct fields if the short name clashes with an outer scope column

Medium severityquery

Power BI Refresh Error:
AMBIGUOUS_REFERENCE

What does this error mean?

A column or field name referenced in the query matches more than one attribute in scope, making it impossible for Spark SQL to determine which one to use.

Common causes

1JOIN between two tables that both contain a column with the same name, referenced without a table qualifier
2SELECT * used in a subquery or CTE, causing duplicate column names to propagate
3Aliased expressions reusing the same name as source columns within the same SELECT list
4LATERAL VIEW or EXPLODE producing a column name already present in the outer query
5Nested structs accessed with a short field name that exists at multiple nesting levels

How to fix it

1Qualify the ambiguous column with its table or alias: `table_a.column_name` instead of just `column_name`
2Replace SELECT * with explicit column lists, using aliases where names overlap
3Rename conflicting columns with AS in the subquery or CTE before referencing them in the outer query
4Run `DESCRIBE <table>` on all joined tables to identify overlapping column names before writing the query
5Use backtick quoting for struct fields if the short name clashes with an outer scope column

Frequently asked questions

Why did this query work before a schema change?

Adding a new column to a source table with the same name as a column in a joined table will introduce ambiguity in existing queries that previously had no conflict.

Does this error occur in Delta Live Tables?

Yes. DLT pipelines using SQL datasets are subject to the same Spark SQL resolver rules and will throw AMBIGUOUS_REFERENCE under the same conditions.