Twitter application oauth started returning error

Question

I've been using code based on Jon Hurlock's Twitter Application-only Authentication App for over a year now with no problem, and about 2 days ago it started returning this error when trying to generate a bearer token:

Invalid or expired token, code:89

My code is slightly altered to force it to check for SSL, since the page is not on an SSL-enabled domain. I have curl pull in the latest cacert.pem file.

This is application level oauth, NOT individual person oauth. So each time a call is made I generate a bearer token, make an API call, and then invalidate the bearer token. You can see his original code here (I pulled the latest version for the part I use): https://github.com/jonhurlock/Twitter-Application-Only-Authentication-OAuth-PHP/blob/master/Oauth.php

THis is the code used to get a bearer token. Note I only have to include the Application's key and secret, there is no user involved and a user never has to allow the app nor authenticate it:

    // Step 1
// step 1.1 - url encode the consumer_key and consumer_secret in accordance with RFC 1738
$encoded_consumer_key = urlencode(CONSUMER_KEY);
$encoded_consumer_secret = urlencode(CONSUMER_SECRET);
// step 1.2 - concatinate encoded consumer, a colon character and the encoded consumer secret
$bearer_token = $encoded_consumer_key.':'.$encoded_consumer_secret;
// step 1.3 - base64-encode bearer token
$base64_encoded_bearer_token = base64_encode($bearer_token);
// step 2
$url = "https://api.twitter.com/oauth2/token"; // url to send data to for authentication
$headers = array( 
    "POST /oauth2/token HTTP/1.1", 
    "Host: api.twitter.com", 
    "User-Agent: Twitter App-Only Search",
    "Authorization: Basic ".$base64_encoded_bearer_token,
    "Content-Type: application/x-www-form-urlencoded;charset=UTF-8"
); 

$ch = curl_init();  // setup a curl
curl_setopt($ch, CURLOPT_URL,$url);  // set url to send to
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers); // set custom headers
curl_setopt($ch, CURLOPT_POST, 1); // send as post
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); // return output
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, True);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($ch, CURLOPT_CAINFO, "/directory/path/cacert2014.pem");
curl_setopt($ch, CURLOPT_POSTFIELDS, "grant_type=client_credentials"); 
$header = curl_setopt($ch, CURLOPT_HEADER, 1); // send custom headers
$httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
$retrievedhtml = curl_exec ($ch); // execute the curl
curl_close($ch); // close the curl

Answer 1

Here is what I found (using the same library from John Hurlock). The Bearer Token should be cached.

This particular implementation will ask for a new Bearer Token for every request, Twitter expects that we will cache this token and will return errors and sometimes a 403 forbidden if we do not.

In my case I turned off twitter for a period of time on the site, and then after caching the Bearer Token turned it back on. Everything is back for now. You could also switch to a new twitter app in your developer console instead of waiting.

I cached my Token in Memcache, but you may choose to do something different. Good luck!