I have configured Moodle in all ways to receive API calls, and am able to make successful API calls from Postman, the address bar of any web browser, etc., but am having an issue translating it into working in Apex. Through testing, I believe I have narrowed things down to one question that if answered will solve the problem:

I have enabled "http://[mymoodleinstance].com" as a Remote Site in Salesforce.

If I try to make a callout to the api endpoint for my instance, "http://[mymoodleinstance].com/webservice/rest/server.php" from the normal address bar in any web-browser window (or from Postman, etc.), I will at least get the error message (letting me know an attempt to associate with my Moodle instance has been initiated and recognized by the system as an attempt) that says "invalid token," XML that is a response from the Moodle system.

If I try to access that same endpoint using Apex code, "http://[mymoodleinstance].com/webservice/rest/server.php", my Apex code being this:

Http H = new Http();

    HttpRequest Req = new HttpRequest();


            HttpResponse Res = H.send(Req);


I get a debug message that says "Bad Request, 400", all of that stuff. Here is the exact message if that helps (the exact tags that come back with the response as well):

<title>400 Bad Request</title>
<h1>Bad Request</h1>
<p>Your browser sent a request that this server could not understand.<br />
<p>Additionally, a 400 Bad Request
error was encountered while trying to use an ErrorDocument to handle the request.</p>

Any thoughts? Why would something work in Postman and as a normal, address-bar request and not in Apex? I've tried:

  • Including and removing the headers that are generated with Postman requests, but then the request still work in the address bar, which has no headers
  • Variations of html encoding, using EncodingUtil
  • 2
    Probably a missing header. Although sending a POST request without a body may also be the culprit. I suggest you examine the headers on your successful requests and include them from Apex as well.
    – Adrian Larson
    Commented Nov 11, 2016 at 16:23
  • Already did. I included this in the last part of the post in the section of "things I've tried." Commented Nov 11, 2016 at 16:40
  • Maybe using the address bar sends an empty body? The api is completely structured around using url parameters and nothing in the body. Maybe Postman, even though the body is blank, does send an empty body. Let me try this. Thanks again for reponding Commented Nov 11, 2016 at 16:43
  • Adrian! That was it! Nice! Thank you so much! Maybe make an answer so I can mark it as the best one so you can get street cred? Thanks, again! You solved a problem I have been beating my head against for quite some time. Thanks, I really appreciate it. Thanks Commented Nov 11, 2016 at 16:46

1 Answer 1


When I've seen issues like this one before, it was usually caused by a missing header. I suggest you examine the headers on your successful requests and include them from Apex as well.

Sending your POST request without a body defined may also be the culprit. I would try setting one.


(sounds like a null body was in fact issue)

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