What causes UNRESOLVED_MAP_KEY?

Accessing a MAP column with a non-constant or non-literal key at parse time. Referencing a map key that does not exist — Databricks returns NULL by default, but in ANSI mode may raise an error. Using a column reference as the map key in a context where only constants are allowed. Schema drift where a column previously of MAP type was changed to STRING or STRUCT

How do I fix UNRESOLVED_MAP_KEY?

Use a string literal as the map key: `map_col['my_key']`. If the key is dynamic, use `element_at(map_col, key_col)` which accepts column references. Wrap map access in `try_element_at()` to safely return NULL for missing keys without erroring. Run `DESCRIBE TABLE ` to confirm the column is still of MAP type after any schema evolution. Enable `spark.sql.ansi.enabled=false` to allow NULL returns on missing keys instead of errors (not recommended for production)

Low severityquery

Power BI Refresh Error:
UNRESOLVED_MAP_KEY

What does this error mean?

A map key accessed with subscript notation (`map_col['key']`) could not be resolved because the key is not a constant expression or the map column itself is not recognised.

Common causes

1Accessing a MAP column with a non-constant or non-literal key at parse time
2Referencing a map key that does not exist — Databricks returns NULL by default, but in ANSI mode may raise an error
3Using a column reference as the map key in a context where only constants are allowed
4Schema drift where a column previously of MAP type was changed to STRING or STRUCT

How to fix it

1Use a string literal as the map key: `map_col['my_key']`
2If the key is dynamic, use `element_at(map_col, key_col)` which accepts column references
3Wrap map access in `try_element_at()` to safely return NULL for missing keys without erroring
4Run `DESCRIBE TABLE <table>` to confirm the column is still of MAP type after any schema evolution
5Enable `spark.sql.ansi.enabled=false` to allow NULL returns on missing keys instead of errors (not recommended for production)

Frequently asked questions

What is the difference between `map['key']` and `element_at(map, 'key')`?

`map['key']` uses subscript notation and requires a constant key. `element_at(map, key_col)` accepts a column reference and is more flexible for dynamic key lookups.