[mjn]

Here's an explanation Paul Graham posted ~6 years ago: https://news.ycombinator.com/item?id=17705

The short of it is that HN uses closures stored server-side to maintain state in various places throughout the site, and purges old closures regularly. As usage has gone up, what counts as an "old" closure is now probably unreasonably short. Restarting HN also invalidates all existing closures.

[Randgalt]

This doesn't excuse the awful user experience. Instead of a terse message there should be a reasonable message with a link to refresh.

[midnitewarrior]

Agree! HN embodies the startup culture. Unfortunately, the user experience here is of an abandoned startup web site.

There is little excuse for such a poor user experience here. At least give me a link back to the home page and don't be so cryptic with the message...

[strict9]

It's inexcusable to use a technical implementation decision to justify a poor user experience. That's what the HN response is every time.