3
It's seems like you need to update your PHP version to 5.6.20 or higher before updating to WordPress 5.2.2 because WordPress 5.2.2 require PHP v5.6.20 or higher to run.
2
Because your rules conflict...
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^\.]+)$ $1.php [NC]
Your first rule matches a request of the form /username and rewrites this to username.php, before your second rule gets a chance to see the request. username.php does not match your second rule.
One way to avoid this ...
Only top voted, non community-wiki answers of a minimum length are eligible
