Get all custom_post_type posts + blog posts from one category in a single query

That should work. Make sure there’re no typos in your custom post type name or where you register the post type.

If that fails try using:

'post_type' => 'any'

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)