3 child sites on server working fine. Then, 2 fail to connect with 404 error, but Test connection is OK

I have 7 child sites connected to MainWP, 4 on the same server as MainWP and 3 sites on another server. All were set up and working fine for about 6 months. Then, out of the blue, 2 child sites on the second server won’t connect, but the 3rd site on this server still connects.

When I try to reconnect the Test Connection is successful with a 200 response code, but when I add the admin name and try to connect, I get “MainWP Child plugin not detected or could not be reached!”. The response code renders as “Not Found | The requested URL was not found on this server. | Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.”

I’ve tried:

  • disabling the security plugin
  • stripping out all code from .htaccess
  • disabling all other plugins
  • enabling a WordPress theme (Twenty-Twenty)

Any other suggestions? I would normally check with the host, but as one site on the server still connects fine, I’m unsure of the issue is there.


If I was in your position, I would start with looking at any new security plugins, clear the caches, and then test again. It is possible your hosting provider does some form of caching.

Thanks for the reply, which has been fuel for my troubleshooting fire. I’ve checked again, and with the .htaccess files disabled on both parent and child site, and the security plugin disabled on the parent site, I can successfully add the child sites to MainWP. Now I know where to look for the conflict. Thanks for your help!

I’ll keep my fingers crossed for ya. I know caching can be a huge issue.


Thanks for the update. I’m glad you got it working.

Spoke too soon unfortunately. The two sites disconnected again. I tried the same configuration as last time (disable both htaccess files and security plugins) but the sites will not reconnect. I have checked with the host, who have tried to connect and then disabled some ModSec rules, but to no avail. The server is Litespeed and the site uses the Litespeed Cache plugin. All caches have been clearer. I’m drawing a blank.


Would you mind opening a private Help Desk ticket so we can collect some additional information & investigate further?

This is the system report from the child site: WP Child - Pastebin.com
And from the parent site: WP Main - Pastebin.com

(* Note that the wp-includes/class-wp-hook.php error is present on all the child sites, 5 of which connect without any issues.


I can see that you tried disabling security plugins (NinjaFirewall from what I can see in the reports) on the Dashboard. Can you try temporarily disabling it on both the Dashboard and Child sites and see if that helps?

Can you also try temporarily disabling all other plugins, including LiteSpeed Cache, on the Child site and see if that helps?

We have received your ticket regarding the issue. I’ll update this thread when I have more information.

Please see my Help Desk reply.

Update. Today, the two problematic child sites have reconnected to the MainWP dashboard. I will monitor for a week and update.

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Great, thanks for letting us know.

Hi @barnez

Just to check in with you - did you experience any further issues with those two sites?

Hi @bojan,

Thanks for checking up. The two child sites stayed connected for several days, then disconnected when I tried to sync data manually in the dashboard. After a few days they connected again, and stayed connected for 4 days, syncing data automatically once a day. The sites are thus syncing fine automatically (on a cron job I assume). However, if I “Sync Dashboard with Child Sites” or “Reconnect” manually, then the two problematic child sites disconnect again for a period of days, after which they reconnect through the syncing via the cron job.

Thanks for the update. If you wish, we can continue solving this via the existing ticket.

Thanks. I have reopened the existing ticket via the helpdesk.

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