New multisites error out

Very new to all this. I have converted our WordPress instance to Multisite. I can create new sites, but when I try to go to the dashboard I get the “There has been a critical error on this website” error.

My wp-config.php file:

define('MULTISITE', true);
define('SUBDOMAIN_INSTALL', true);
define('DOMAIN_CURRENT_SITE', 'www.wf.catholic.edu.au');
define('PATH_CURRENT_SITE', '/');
define('SITE_ID_CURRENT_SITE', 1);
define('BLOG_ID_CURRENT_SITE', 1);

define('ADMIN_COOKIE_PATH', '/'); 
define('COOKIEPATH', ''); 
define('SITECOOKIEPATH', ''); 
define('COOKIE_DOMAIN', false);

And I have included this in my .htaccess file:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
RewriteBase /
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^wp-admin$ wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^(wp-(content|admin|includes).*) $1 [L]
RewriteRule ^(.*\.php)$ $1 [L]
RewriteRule . index.php [L]
</IfModule>

# END WordPress

My .htaccess file also contains some other code for redirecting each of our school’s webpages (see below).

# php -- BEGIN cPanel-generated handler, do not edit
# This domain inherits the “PHP” package.
# php -- END cPanel-generated handler, do not edit
RewriteCond %{HTTP_HOST} ^bourke\.catholic\.edu\.au$ [OR]
RewriteCond %{HTTP_HOST} ^www\.bourke\.catholic\.edu\.au$
RewriteRule ^/?$ "https\:\/\/www\.wf\.catholic\.edu\.au\/schools\/bourke\/" [R=301,L]

There are more of these in the file but I have left them out. Is there any obvious reason why my new sites are not working?

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