Facebook Send dialog with API Error code: 100 ('link' is invalid) - facebook

Question

I want to provide users with the ability to send money to their Facebook friends through our app (Exvo) by the means of sending an URL to the invitation page via Facebook.
I'm using the 'Send' Facebook dialog (with a redirect to the Facebook webiste). The exact url I'm redirecting the user to is (to field has been redacted):
https://www.facebook.com/dialog/send?app_id=637466739616439&description=You+can+create+an+Exvo+Account+to+accept+this+money+transfer.&display=page&link=https%3A%2F%2Fwww.exvo.com%2Finvitations%2F9fb77bda665f0ae8f58843daec80a29b&name=Pawe%C5%82+Go%C5%9Bcicki+would+like+to+send+you+0.01+EUR&picture=https%3A%2F%2Fthemes.exvo.com%2Fstylesheets%2Fimages%2Fcustom_images%2Flogo.png&redirect_uri=https%3A%2F%2Fwww.exvo.com&to=username
This present me with a Facebook 'Send' dialog. When I type a custom message and press 'Send', I'm presented with this error:
API Error Code: 100
API Error Description: Invalid parameter
Error Message: 'link' is invalid.
The link param (extracted from the above URL and decoded) is this:
https://www.exvo.com/invitations/9fb77bda665f0ae8f58843daec80a29b
which is a valid URL, returning a proper 200 response. Using the Facebook debugger I can see that the provided URL does not generate any errors:
https://developers.facebook.com/tools/debug/og/object?q=https%3A%2F%2Fwww.exvo.com%2Finvitations%2F9fb77bda665f0ae8f58843daec80a29b
Only warnings about inferred properties (I have added those at one point as well, but it did not help).
Also note, that once in a while (like 1 in 10), when I click 'Send', the message gets through and I don't see any errors, which makes it even weirder.
Why is this error happening? What am I doing wrong?

Answer 1

This might not have been the problem in your case, but just for discoverability: make sure that the URL you are sharing is publicly available on the internet (i.e. not within your firewall or on a local computer). FB needs to visit your URL to verify its authenticity.

Answer 2

Like mpcabd has pointed out above, make sure to remove anything with fb, fbdev, facebook in the url because when I did, it solved the issue for me. It is probably a bug or a security measure by Facebook. You are always required to pass a redirect_uri with the link and try mentioning a title as well.
Also your link and redirect_uri must be within your domain that you have provided for the app. Ex: if your app domain in app settings is http://stackexchange.com, you cannot share a link like say https://stackoverflow.com/apps/php/fbsdk/etc/login.php, instead you have to share the link https://stackexchange.com/apps/php/etc/login.php which has worked for me
echo "<a href='https://www.facebook.com/dialog/send?app_id=YOUR_APP_ID&name=Thanks&link=".$linkToShare."&redirect_uri=".$linkToRedirectTo."'/>Send</a>";
You can also assign $title to something.

Answer 3

I figured out something weird, the same thing happened today on the site I manage, the problem seemed to be that the link contains the word facebook in it, so try to remove [facebook, fb, or f if it was a whole word] from your url, it should work, I had a url like open/ID/facebook/ and the only way it worked when I changed it to fopen/ID/ which looks stupid!
So may be in your case this is the problem:
https://www.exvo.com/invitations/9fb77bda665f0ae8f58843daec80a29b
Try to change your url to something without fb or facebook or anything similar.

Answer 4

I had this issue using the send dialog only. I was using dynamic querystring parameters on a common URL. The common URL has been scraped by Facebook but each iteration of the common URL and the querystring parameters would result in this error if Facebook had not scraped that exact URL previously.
I fixed the issue by forcing Facebook to scrape the URL before I attempt to send it via the FB UI Send Dialog. Use the FB API to hit graph.facebook.com with the URL posted in the id parameter and a scrape parameter set to true.
Like so:
FB.api('https://graph.facebook.com/', 'post', {
id: '[URL]',
scrape: true
}, function(response) {
FB.ui({
method: 'send',
name: '[name]',
picture: '[Picture URL]',
link: '[URL]',
description: '[description]'
});
});
I also answered with this solution to the same problem here.

Answer 5

Doing the following fixed it for me:
shorter token (this string in the link param: 9fb77bda665f0ae8f58843daec80a29b, which was 32 characters long, now is at 16) as advised by gkimsal
accepting October 2013 breaking changes, which required me to introduce OpenGraph tags to the page and drop name, description and picture_uri params that I was including when constructing the Send dialog redirect uri
Now Facebook, before displaying the Send dialog to the user, must fetch my page beforehand to retrieve the data (from OG: title, description and image) required to display a proper dialog to the user. I think this is what helped the most in my case.