So I cannot find any reason I am seeing the below behavior and if anybody has some insight it will be greatly appreciated.
Basically I am using the FB.UI from the JavaScript SDK to send a message to a user with a link. The link ends with a Guid, like http://www.domainname.com/register/33a1a0ae-e0fe-4eb6-9bf9-146d5492e3d6. This works sometimes, but occasionally fails with a generic 500 error from FB.
I have pulled out the HTTP POST request and have found a solution that I can recreate, unfortunately I cannot share the access code to allow SO users to actually run it (I replaced all sensitive parameters). Below are two identical requests that differ only in the Guid. The first succeeds every time and the second fails every time. I have numerous Guids that are doing this which makes if unreliable.
I tested both of these urls:
with the js sdk send method, and indeed the first url resulted in a 500 from facebook, while the first managed to send it.
I can’t understand why the first UID triggers an error while the second does not.
The reason I kept asking for a working example of such urls is that when you share a url using facebook, they scrap that url (unless it’s already in their cache) and extract meta data of that url so that a feed story can be composed.
Since the urls that I was trying are not accessible for facebook it might somehow trigger that error.
If I try this url:
http://laine.webhop.org/tresendas/register/33a1a0ae-e0fe-4eb6-9bf9-146d5492e3d6
then it works and I don’t get the server error, even though it has the same UID as the first url I tried.
I suggest that you try to use urls accessible to facebook, if you still get errors for certain UIDs, then you should probably open a new bug report.