Title: 422 Mastodon::HostValidationError
Last modified: November 20, 2022

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# 422 Mastodon::HostValidationError

 *  Resolved [ncottech](https://wordpress.org/support/users/ncottech/)
 * (@ncottech)
 * [3 years, 6 months ago](https://wordpress.org/support/topic/422-mastodonhostvalidationerror/)
 * I’m trying to set up the plugin in my self hosted WordPress server, but whenever
   I try to follow my blog’s user, I get this:
 * 422 Mastodon::HostValidationError on [https://plot88.uk/.well-known/webfinger?resource=acct:james@plot88.uk](https://plot88.uk/.well-known/webfinger?resource=acct:james@plot88.uk)
 * If I visit that URL, I get JSON back, and if I use webfinger.net, it also shows
   me the JSON data.
 * My user page [https://plot88.uk/author/james/](https://plot88.uk/author/james/)
   just takes me to a regular wordpress page containing all my posts, is that what’s
   supposed to happen? I’m having problems figuring out what to even look at to 
   debug this.
 * The wordpress server is serving HTTP using nginx, behind an nginx reverse proxy
   that’s using Let’s Encrypt for an SSL certificate.

Viewing 5 replies - 1 through 5 (of 5 total)

 *  Plugin Author [Matthias Pfefferle](https://wordpress.org/support/users/pfefferle/)
 * (@pfefferle)
 * [3 years, 6 months ago](https://wordpress.org/support/topic/422-mastodonhostvalidationerror/#post-16217097)
 * This seems to be an issue on Mastodons side: [https://github.com/mastodon/mastodon/issues/7832#issuecomment-627132802](https://github.com/mastodon/mastodon/issues/7832#issuecomment-627132802)
 *  Plugin Author [Matthias Pfefferle](https://wordpress.org/support/users/pfefferle/)
 * (@pfefferle)
 * [3 years, 6 months ago](https://wordpress.org/support/topic/422-mastodonhostvalidationerror/#post-16217102)
 * I had a look at your setup and everything looks like expected, so it seems to
   be something of your NGINX/SSL/Reverse Proxy setup, that mastodon does not like.
   I guess. To proof it, I followed you on pixelfed.social without problems (you
   should see my pixelfed in your followers list now).
 *  Plugin Author [Matthias Pfefferle](https://wordpress.org/support/users/pfefferle/)
 * (@pfefferle)
 * [3 years, 6 months ago](https://wordpress.org/support/topic/422-mastodonhostvalidationerror/#post-16217122)
 * [https://plot88.uk/wp-json/activitypub/1.0/users/1/followers](https://plot88.uk/wp-json/activitypub/1.0/users/1/followers)
   🙂
 *  Thread Starter [ncottech](https://wordpress.org/support/users/ncottech/)
 * (@ncottech)
 * [3 years, 6 months ago](https://wordpress.org/support/topic/422-mastodonhostvalidationerror/#post-16237994)
 * Yeah I can’t figure it out. I suspect there’s some voodoo required in my nginx
   setup. I bet if my webserver was directly accessible, it’d work fine. Especially
   if you can follow it from other fedi clients.
 * Ah well, I’ll close this, thanks for trying 🙂
 * Sorry future people, I couldn’t fix this and didn’t know why it was broken. It’s
   probably something obscure in my setup.
 *  Thread Starter [ncottech](https://wordpress.org/support/users/ncottech/)
 * (@ncottech)
 * [3 years, 2 months ago](https://wordpress.org/support/topic/422-mastodonhostvalidationerror/#post-16616906)
 * I have “fixed” it!
 * There was[ a patch made to Mastodon](https://git.asonix.dog/asonix/mastodon/commit/2e8a492e8843aa958c53636b24cf4d344e7ca47d)
   way back when that means you can’t follow people on servers with private IP addresses.
 * So if you have a mastodon server and other ActivityPub servers on the same public
   IP address and you use reverse proxies to route requests to internal IP addresses
   it’ll fail.
 * And if you understand this, you understand either how to fix it (turn on loopback
   NAT on your router) or will know it’s impossible to fix on your setup depending
   on your router.

Viewing 5 replies - 1 through 5 (of 5 total)

The topic ‘422 Mastodon::HostValidationError’ is closed to new replies.

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## Tags

 * [mastodon](https://wordpress.org/support/topic-tag/mastodon/)

 * 5 replies
 * 2 participants
 * Last reply from: [ncottech](https://wordpress.org/support/users/ncottech/)
 * Last activity: [3 years, 2 months ago](https://wordpress.org/support/topic/422-mastodonhostvalidationerror/#post-16616906)
 * Status: resolved