I can't add testers to iTunes Connect: Users and Roles → TestFlight Beta Testers → Internal

I'm a developer for a small company's team. I am trying to set up Apple's TestFlight service.

I have a Beta submitted for a new release. I have turned on TestFlight testing for this build. However, when I try to invite testers, I am told that I need to enable some users for this role.

When I go to the "Users and Roles – TestFlight Beta Testers – Internal" section of iTunes connect, I see the list of other people in the company's team. There is a check mark to the left of each person to select them. iTunes Connect won't allow me to select any of the users and doesn't give an error.

How can I add testers?

Solution

In my case, this happened because I was set up with the Technical role in the iTunes Connect team.

Users with the Technical role are not authorised to add internal beta testers.

You need to find someone within the team who has either the Admin or Legal role in iTunes connect.

This person can then either:

Set up testers themself.
Set you up to have the Admin role, at which point, you will be able to add testers yourself.

Without the Admin or Legal role, you will not be able to set up testers.

The UI does not seem to have any feedback to inform you of this, which is unfortunate.