Adding to @theJusarg Justin Sargent’s summary, there was one other thing I had to do:
To solve this error make sure you do the following:
- You have confirmed your email with twitter
- You set you application settings to Read/Write
- You reset your keys/token
- WAIT - Took twitter a little bit to reflect the changes I made to my app, once it updated though it fixed the error (so give twitter an hour or so to update).
- Have OAuth-authenticated users log out of your app and go back through the OAuth login process
For some reason, after I did #3 and restarted my app with the new keys/token, my users who had gone through OAuth on the previous keys/token were still able to interact with Twitter with their previous OAuth credentials. It looked like I had done everything (i.e. steps 1-4) but it required having them go back through the OAuth process to get it working.