start creating a new media type. leave "name" field empty, click "add".
error message states :

Incorrect value for field "description": cannot be empty.

a simple fix might be changing the field name/id.

while ZBX-7197 asks for a better, more generic solution, in this specific case the error message does not match the field label at all.

it also looks like this was already fixed for 2.1.0, but regressed later: ZBX-5142