Getting intermittent 401 errors retrieving new access token

Various users of our private OAuth app are getting intermittent errors when the app tries to retrieve a new access token using a stored refresh token.

Could not retrieve access token. Error: 401

PHP Code below.
// $ID=client ID, $Scret = Client Secret, $rtoken = refresh token
function newAccToken($ID, $Secret, $rtoken)


$b64idsec = base64_encode($ID.":".$Secret);

$header = array(“Authorization: Basic {$b64idsec}”);

$curl = curl_init();

$url = “”;

curl_setopt_array($curl, array(

    CURLOPT_URL => $url,



    CURLOPT_POST => true,

    CURLOPT_POSTFIELDS => $content,

     CURLOPT_HTTPHEADER => $header


$response = curl_exec($curl);

$ret['response_code']=curl_getinfo($curl, CURLINFO_RESPONSE_CODE); // code > 200 error



return $ret;


Hey @greg.ross,

Thank you for reaching out to the Zoom Developer Forum. First, It’s important to note that the refresh_token will only work for the currently access_token. If a new access_token is requested separately then this will invalidate the refresh_token that you have.

If that isn’t helpful, are you able to provide the full response body that you’re seeing when you encounter this issue?


Thank you.
I use the existing fresh token to get a new access token before using it and then save the new refresh token for another time. The same code works consistently for many api requests. I will change the code so it provides a full response body upon error.

Hey @greg.ross,

Thank you for the update. I’ll advise further when we have the request body to review.


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