Hi,

Thanks again for your help earlier.

I was finally able to resolve the issue. The problem came from a redirection rule in my .htaccess file that was forcing all requests to index.php to be redirected to /, including POST requests.

Here's the rule I had in place :

RewriteCond %{THE_REQUEST} ^[A-Z]{3,}\s/index\.php[?\s] [NC]
RewriteRule ^index\.php$ / [R=301,L]

This was originally added for SEO reasons, but it ended up breaking the "Add to Cart" function in EasyStore, because :

POST + 301 redirect → becomes a GET → EasyStore returns 405 Method Not Allowed

THE SOLUTION :

I updated the rule to apply only for GET requests by adding this condition:

RewriteCond %{REQUEST_METHOD} =GET

So the final working version is:

RewriteCond %{REQUEST_METHOD} =GET
RewriteCond %{THE_REQUEST} ^[A-Z]{3,}\s/index\.php[?\s] [NC]
RewriteRule ^index\.php$ / [R=301,L]

Now everything works perfectly — including Matomo, Redis cache, and my custom price script.

Thanks again for pointing me in the right direction!

Best regards,