HTML5 validator.w3.org

Question

My site was valid until today, wondering wether it is my site's or the validator's fault.

I am getting this message:

The error encountered was: 500 Can't connect to localhost:8888 (connect: Connection refused)

Answer 1

HTTP Error 500 is an Internal Server Error, so that will be their fault. Try validator.nu whilst you are waiting.

Answer 2

W3C validator maintainer here. Tip: Next time you see that message, try validating your document directly at http://validator.w3.org/nu/ instead.

Because if you see that 500 error it means the validator is trying to reach the HTML5 backend, which runs as a separate service/process responding at localhost:8888 on the validator host.

But we actually run several validator hosts, round-robin, so if you see that 500 error it could mean that only one of the HTML5 backends on one of the hosts is temporarily down. And if you go to http://validator.w3.org/nu/ you might get lucky and hit a different host and it'll work.

On the other hand if you get a 404 from http://validator.w3.org/nu/ it most likely means you caught me in the middle of restarting/redeploying the W3C HTML5 validator backends to pull in changes I've made to the sources from https://github.com/validator/validator

But that never takes me more than a few minutes, so on your end you should never be seeing that 500 error for more than, say, 10 minutes at most. So if/when you do see it for any longer than that, please report it either by tweeting to @w3c or @sideshowbarker on twitter, or pinging me on IRC (MikeSmith on #whatwg or #w3c on irc.freenode.net).