I created a test app and I tried to test the POST /oauth/request_token call using the OAuth Tool to generate a valid request. I copied the curl command generated on the page
https://dev.twitter.com/oauth/tools/signature-generator/<app_id>
and run it on Mac terminal. I got HTP/1.1 401 Authorization Required error.
I’ve seen other forum post having the same issue but not yet resolved.
Can someone from Twitter please help us check?
Also, I notice that in the curl command generated, oauth_callback is present in the signature base string but missing in the authorization header.