Facebook: “Sorry, there was a problem with this link” – should we worry?

If you run a WordPress blog and have WP.com stats installed via Jetpack, check out whether new link groups appeared in the Referrers section:

• l.facebook.com – from desktop computers
• lm.facebook.com – from mobile devices

These links are an extra source on top of regular links from Facebook, marked with a Facebook icon. They are something to observe – and something to potentially worry about.

They are in fact warning pages, where Facebook displays a concern that the link to your site may be insecure. The message goes:

On average, since it all started, one-fifth on the links from Facebook go through warning pages.

Facebook is redirecting all outgoing links through the l.facebook.com or lm.facebook.com, but sometimes the warning is being displayed instead of moving directly to a destination site.

Why it’s important to take the issue seriously. The warning does not only prevent the Facebook user from clicking on the current link. Lost clicks are nothing compared to the other effect – in the longer run such warnings may spoil the image of your blog.

I’ve run the posts in question through Facebook Debugger – everything was OK, the response code was 200. I’ve also used HTML validation – nothing was wrong, either.

The issue doesn’t have anything to do with recent changes to Facebook News Feed, designed to fight spammy stories. The posts from my blog with a traffic via l.facebook.com are distributed through Buffer right after they are published.

What’s even more interesting is that, as I said before, only one-fifth of clicks goes through warning pages. The rest is just fine.

One possible reason (and I wish it was the right one) is that loading the destination page takes a bit longer than usual – enough to let WP.com to count the traffic from l.facebook.com – although the warning was not actually displayed.

There is not much info on the web about the “Sorry, there was a problem with this link” issue.

Funny thing is that when you search Google for answers, one of the first results shows that Facebook doesn’t trust a page that belongs to… Facebook. The warning is displayed for the help section of Instagram, as seen on the screenshot below.

Updated on 23.04.2014

While l.facebook.com links from Jetpack referral section open warning pages, I’ve extensively checked the posts – but clicking on them directly from Facebook. Also, I asked my friends to open these links, to get a portfolio of options:

• different users (not only Facebook page owners, managers),
• different IP numbers,
• users who didn’t like my Facebook page,
• users who are not logged in.

The result: I haven’t found a single link on Facebook that would end up in the warning page.

What you should do is to locate on Facebook the posts that bring most l.facebook.com traffic and try to click on them using different devices, browsers, and locations.

The l.facebook.com parameters started to appear in stats around April 5, 2014. This applies to Jetpack, but also to Google Analytics.

Once WordPress blogs, packed with heavy code, may be seen by Facebook as potentially dangerous, I’ve found out that the warning links appeared also in my simple Tumblr photo blog, where I have Google Analytics installed as well.

Digging more about the issue let find out that since 2008 Facebook is using a set of tools called “link shim”.

In general, link shim is designed to protect Facebook users from malicious URLs.

How it works. Every time a link is clicked on Facebook, the link shim will check the URL against a list of malicious links – internally on Facebook, but also from external partners: McAfee, Google, Web of Trust, and Websense.

If we detect that a URL is malicious, we will display an interstitial page before the browser actually requests the suspicious page.

However, what link shim also does is that it enables more accurate external analytics.

It is, for instance, used to identify traffic from Facebook, if users are on HTTPS protocol. When they click on HTTP link, the browser recognizes it as the traffic from an unknown origin. Therefore link shim is being used to send the correct referer header.

To summarize: it’s probable that Facebook started to include in their link shim scheme a new parameter, that is being seen in the stats as l.facebook.com, and that in fact doesn’t mean users were seeing warning pages.

To find whether you should worry about the issue, check out the traffic from Facebook since April 5. If it decreased, it’s probable you were affected by new parameters added to Facebook link shim.

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