Unexpected token “name” of value “OR” (“end of statement block” expected). Twig

I recently had following error from twig template engine:

Unexpected token "name" of value "OR" ("end of statement block" expected).
Unexpected token "name" of value "AND" ("end of statement block" expected).

Stackoverflow searches were unsuccessful. But the solution was really easy:

You have to use lowercase “or” – “and”. Twig does not support uppercase.