A bunch of Twitter API clients which upgraded from v1 API to the free v2 API were suddenly suspended. The portal tells you to file an appeal, however all "contact support" links lead to a dead end.

I believe the reason this changed is due to a change in the permission model, might be a bug as it's very unintuitive as you will see in a minute.

How to fix it

• Go to the Developer Portal and delete the suspended app
• create a new app under the existing project
• If you generate authentiation tokens, notice how after creating them it says they are "read only", not allowing you to tweet (which is the only thing you can do with the free API)
• Go to settings and scroll down to "User authentication set up"
• Change the permissions to "read and write", under callback and website URL you can put anything as it doesn't matter.
• This will generate oauth keys but you won't need them
• Now to go back to "Keys and tokens" and (re)generate both the keys and token, even if you created them before already
• That's it, now you should see the access token has "read and write" permissions and you can add the new keys to your application!