Subsites in Multisite throw 404 in wp-admin

Question

I have a multisite (sub directory) network with around 10 sites that has been running for several months in its current environment without any issues. Suddenly (without any code changes) I'm getting 404 errors when trying to access wp-admin for each subsite (the frontend for all sites and wp-admin for the main site works fine).

For example:

• subsite1/wp-admin - the page loads but all resources are throwing 404s. Getting errors in the console like:

  Refused to apply style from '.../wp-admin/load-styles.php...&ver=4.9.8' because its MIME type ('text/html') is not a supported stylesheet MIME type, and strict MIME checking is enabled.

  load-scripts.php:1 Failed to load resource: the server responded with a status of 404 ()

Then if I try to access a page within wp-admin like: subsite1/wp-admin/anything.php, the page throws a 404.

This is my htaccess file:

RewriteEngine On
RewriteBase /
RewriteCond %{HTTPS} off
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) $2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ $2 [L]
RewriteRule . index.php [L]

Any ideas at all? Thanks

Answer 1

@user2753924,

I was experiencing a similar(if not the same) issue. I ended up turning PHP-FPM off and that seems to have worked for me.

If you're unsure of how to change this on your hosting account, I'd suggest contacting your host and seeing if they can handle it for you.