I get a 403 Forbidden error during the Microsoft 365 sign-in redirect. How can I fix this?

When trying to connect the Microsoft 365 / Outlook Connector, the Microsoft login works, but after authentication you are redirected back to Joomla and receive a 403 Forbidden error.

Solution

You must explicitly allow the Microsoft 365 callback URL inside your .htaccess file.

Step-by-Step Instructions

1. Open your site’s main .htaccess file located in your Joomla root directory.
2. Find the following line:
   

   RewriteEngine On
   	

3. Below that, locate the administrator / backend section, which usually looks similar to this:

   #### Back-end protection
   RewriteRule ^administrator/?$ - [L]
   RewriteRule ^administrator/index\.(php|html?)$ - [L]
   	

4. Immediately AFTER the backend protection rules, add this snippet:

   <code># Allow any ms365 callback under /index.php/ms365/
   RewriteCond %{REQUEST_URI} ^/administrator/index\.php/ms365/ [NC]
   RewriteRule .* - [L]
   	

Final Example

Your .htaccess should look similar to this:

RewriteEngine On

#### Back-end protection
RewriteRule ^administrator/?$ - [L]
RewriteRule ^administrator/index\.(php|html?)$ - [L]

# Allow any ms365 callback under /index.php/ms365/
RewriteCond %{REQUEST_URI} ^/administrator/index\.php/ms365/ [NC]
RewriteRule .* - [L]