We’ve received numerous reports of such issues recently, and the cause behind each was completely different.
There are a lot of reasons you might not receive alerts. Furthermore, there are multiple kinds of alerts—alerts that appear in your Alerts dropdown, alerts that appear in your Messages dropdown, and email notifications. In order to determine the cause of each incident, we need more information:
- Provide a link to the exact post (or conversation message) that should’ve triggered the alert.
- Very specifically, where did you expect to see the alert? For example, “I expected a red notification counter to appear on my Alerts tab on the website, but it didn’t,” or, “I expected to receive an email.”
- Why should the post have triggered an alert for you? Were you tagged? Is it a thread that you watch? ...a forum that you watch?
Here are the most common causes of failed notifications:
- If you’re having trouble receiving email notifications, you might have a lousy email provider. (Looking at you, Yahoo.) Based on the data we’ve seen, we generally recommend Gmail/G Suite, Outlook.com, and ProtonMail. If you’re using Yahoo, you should strongly consider switching. (I know switching email providers is an absolute pain, so I don’t make this recommendation lightly.) If you’re looking for something that favors privacy and security over features, ProtonMail is the way to go—not that it’s light on features. If you’re not worried about that sort of thing, Gmail is a solid choice.
- If you’re no longer receiving notifications for a forum that you watch, double check that you’re still watching it. It’s surprisingly easy to accidentally unsubscribe. Based on what we’ve observed, people tend to click the Unwatch link by accident, then instinctively click through the confirmation dialog without realizing what it’s about to do.
- XenForo, our forum software, has a few edge cases where a post operation—either to a thread or conversation—can “lock up.” These are known as concurrency bugs, and they’re notoriously difficult to debug. The XenForo development team isn’t much help when it comes to obscure issues like that, since most of their customers aren’t big enough for it to be an issue. We do our best to patch these, but they’re relatively rare (maybe 1 in 1000 posts, very roughly), and they’re time-consuming to fix. We receive automated reports when this happens. These are one-off incidents, so you shouldn’t notice this happening on a regular basis. Recently we did record that some posts succeeded to be added to threads, but locked up during the notification process; this would have resulted in a number of failed notifications, both via email and on-website alert.
- Within the past month or so we logged an event during which some alerts were mysteriously lost. No errors accompanied the event, and it resolved itself before we could fully debug it. We were unable to reproduce the issue in testing and haven’t observed it since. Until we determine the cause, it’s possible that this issue could recur.