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