[Yandex Cloud documentation](../../../index.md) > [Yandex DataLens](../../index.md) > Troubleshooting > Cannot join: key is empty

# [Yandex DataLens] Cannot join: key is empty

`ERR.DS_API.DB.CHYT.INVALID_SORTED_JOIN.KEY_IS_EMPTY`

This error occurs when CHYT cannot extract a join key from the `ON`/`USING` condition.

To fix it, add at least one direct equality between the key columns and make sure the joined columns are included in the sort key prefixes of both tables.