Route error during theme change

[Darkeduar]

I have clean prestashop 8.2.1 installation and i've tried to create child theme for classic theme, i created basic config thats basicly ctrl+c, ctrl+v code from the documentation and i got this error:


So i tried with some other themes i found and none worked so i dont think its my "child theme" fault. Reinstalled presta once again, same error. I'm doing all my testing on Ubuntu 24.04, php 8.1. I've tried to just brute force and change active theme to my child theme in the database in ps_store table but despite having 

assets:

 use_parent_assets: true

in my configuration file no css/js will load.

[El Patron]

This error occurs because a POST request is being made to /modules/improve/design/themes, but the route only allows GET requests. This is usually caused by a theme or module compatibility issue, or a cache/routing problem after a theme change or upgrade.

Try these steps:

1. Clear the PrestaShop and Symfony cache:
2. Delete everything inside /var/cache/ or run php bin/console cache:clear from your shop’s root directory.
3. Check your theme’s compatibility:
4. Make sure the theme you’re switching to is fully compatible with your PrestaShop version, especially if you’re on PrestaShop 8.x.
5. Test with the Classic theme:
6. Switch back to the default Classic theme. If the issue disappears, the new theme likely needs updating for compatibility.
7. Clear your browser cache:
8. Outdated cookies or cache can sometimes cause admin forms to misfire.
9. Check for overrides:
10. Look for any custom code in /override/controllers/admin/ or /modules/ that might interfere with theme management.

probably the themes (assuming free) are crap...consider purchasing a highly reviewed prestashop theme that is compatible with your  ps version