Custom Error Pages

An error page rule decides what visitors see when your server can’t answer a request — down, too slow, or returning a server error.

The three modes

Mode	What the visitor sees
nsin page	nsin’s own error page. Works even when your server is unreachable. Default.
Your own page	HTML you provide, served by nsin. Also works when your server is down.
Pass through	Your server’s own error response, unchanged. Only possible when your server answered.

Create an error page rule

1. Go to Rules → Add Rule → Error Page.
2. Pick the status codes the rule covers — 5xx only, e.g. 500, or 502, 503, 504 together.
3. Pick the mode.
4. For your own page, paste the HTML for each code, plus an optional fallback for any covered code without one.
5. Optionally limit the rule to certain paths.
6. Click Save.

Writing your own page

Inline your CSS — don’t load images, fonts or scripts from your own server, since those requests fail too during an outage. Say what happened and what to try next.

Which codes matter

Error page rules cover 5xx only.

• 502 / 503 / 504 — server didn’t answer, or answered too slowly. Worth customizing.
• 523 — hostname not set up on nsin. Can’t be customized: nsin answers before it knows which site the request is for.

Not covered: 404 and other 4xx (shown as your server sent them), 403 (block rule), 429 (rate limiting) — both come from nsin, not your server, and error page rules don’t touch them.

While developer mode is on

Developer mode adds a temporary, unremovable rule at the top of the list: pass through for every 5xx code, every path. Your server’s own response — stack trace, debug page — reaches the browser instead.

• Runs before your own rules, marked Developer mode in the list.
• Can’t be edited; switch off or delete developer mode to remove it.
• Removed automatically when it ends. If your server doesn’t answer at all, the nsin page still shows.

Caution

While developer mode is on, every visitor sees these errors, not just you. Turn it off when you’re done.

Common questions

My custom page doesn’t show up. Check the rule covers that status code and its paths match. Pass through shows your server’s page on purpose; developer mode shows your server’s raw errors.

Can I redirect instead of showing a page? No — a redirect turns an error into a 200 OK, which confuses browsers and search engines. Show the error, and offer a link.

Visitors saw an nsin page during an outage. That’s the fallback working: your server was unreachable. Set up your own page for 502/503/504, and see Uptime.