If you have a listing on Tripadvisor and it links to your website (that runs under HTTP, rather than HTTPS), you may get the surprise to see that there are no visits coming from Tripadvisor.
In order to fix this issue, you need to switch your website from HTTP to HTTPS.
There is no error in tracking and it doesn’t mean that there are no visits coming from this referral, but Tripadvisor cannot be tracked by any analytics app because they changed their security settings. Here is their response on this matter:
"In mid-March of this year TripAdvisor changed the way it sends data for referral visits from its business listings and, as a consequence, referral data is lost in Google Analytics for many businesses. The reason for this is that TripAdvisor has moved to the HyperText Transfer Protocol Secure (HTTPS). Based on their current setup of this protocol, links to any external website that does not have HTTPS won’t receive the referral data in Google Analytics, meaning our client B&B innkeepers and dude ranches have lost valuable data to track the effectiveness of the dollars spent on having those links to their websites on TripAdvisor. If you discover that there is TripAdvisor data missing in Google Analytics you can take steps to re-establish that important data collection."
NOTE: There is nothing that we (or any other analytics app) can do about it, but this is how Tripadvisor and companies (e.g. Yahoo) set up their security.