Why are there no referral URLs in the Intelligent 404 analytics?

The way Intelligent 404 referral URLs are registered is different from referred page URLs for searches (search origin pages).

For searches, the referral information is added to the URL. When the visitor lands on the search results page, Cludo will grab the referralURL from the query parameters passed to the search results page. This is very reliable because when Cludo adds the referral URL to the query parameters on the page where the search occurred, it will always have a URL.

For Intelligent 404, referral URLs depend on the document.referrer property in JavaScript. This property has some caveats associated with it. For example, the following scenarios will result in the property being empty:

• Direct/manual entry of URL in address bar
• Navigation to page via bookmark
• First page visited in a new tab or page
• Referral came from an external application
• Referral was from https to http
• Behind proxy which strips the referrer from all requests

Some of these outcomes apply to individual users while some could apply to all traffic to a particular 404 page. If it applies to some individual users, the Intelligent 404 analytics are still useful because you can see some of the referrals. If there is a high volume of inbound traffic to a particular page and none of them have referral information, it might be safe to assume that the link comes from something like an external application where it will be stripped for all visitors that land on it.