Unknown 404 error

Hey ! I have a major problem with my website.

Theme used : Twenty Seventeen
Plugins : Akismet, amr shortcode any widget, Facebook Open Graph, Google+ and Twitter Card Tags, Jetpack, MailChimp for WordPress, Multisite Post Duplicator, OneSignal Push Notifications, Rss Post Importer, Super Socializer, Theme Check, WP Super Cache
Hostname : shost.ca
URL: ladiascpora.net
Version of WordPress : 8.4.2

Problems encountered :

After having set up my site yesterday, I decided today to pass it in “multisite” mode to link it with other blogs. The installation seems to be working properly. At the end of the installation, I quickly look at how the sites react. If the sub-blogs have no problems, my blog (the main blog) has a 404 error for all pages, with the inability to modify the settings of Jetpack, saying me : “Error updating parameters. SyntaxError: Unexpected token <in JSON at position 0“.

I do not know what the error is. The change of status (published / draft), URL, creation of new pages always results in a 404. What is this due?

This change involves the modification of two files:

htaccess

RewriteEngine On
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]

wp-config
* Pour plus d’information sur les autres constantes qui peuvent être utilisées
* pour le déboguage, rendez-vous sur le Codex.
*
* @link https://codex.wordpress.org/Debugging_in_WordPress
*/
define(‘WP_DEBUG’, false);

/* Multisite */
define( ‘WP_ALLOW_MULTISITE’, true );
define(‘MULTISITE’, true);
define(‘SUBDOMAIN_INSTALL’, true);
define(‘DOMAIN_CURRENT_SITE’, ‘ladiascpora.net’);
define(‘PATH_CURRENT_SITE’, ‘/’);
define(‘SITE_ID_CURRENT_SITE’, 1);
define(‘BLOG_ID_CURRENT_SITE’, 1);

/* C’est tout, ne touchez pas à ce qui suit ! */

/** Chemin absolu vers le dossier de WordPress. */
if ( !defined(‘ABSPATH’) )
define(‘ABSPATH’, dirname(__FILE__) . ‘/’);

/** Réglage des variables de WordPress et de ses fichiers inclus. */
require_once(ABSPATH . ‘wp-settings.php’);

Thank you by advance.
Paulin.

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