verify-email-bundle | Simple , stylish Email Verification for Symfony | Continuous Deployment library

That composer.json file is a bit of a mess. Some Symfony packages on 5.3, some even on 5.1, and many on 6.

Also you are controlling Symfony versioning from extra.symfony.require, and at the same time from the discrete version constraints. You include some packages that no longer exist on 6.0 (symfony/security-guard), and are missing some that should be installed on a 6.0 version.

It's simply not on an installable state.

I've managed to make it installable changing it like this:

You have conflicting requirements.

On extra.symfony.require you say you want 5.3.*.

But on your individual Symfony requirements you are specifying either ^5.2 or 5.2.* (and in some cases ^5.3 as well).

When a project uses Symfony Flex (as is your case), the presence of extra.symfony.require will be used to restrict what package versions to install for many/most Symfony packages. But only if you do not declare a specific version on your require section.

In this case, you are already specifying a version on the 5.* range on extra.symfony.require. Leave that one like that, and just use * as a version constraint for all the other Symfony Packages in the require section.

(Note that's it's not really all, since some packages are not managed by Flex, just update the ones that have versions declares in the 5.* range)

You'll need to install all extensions needed manually. In your case, you are missing the XSL extension. This should at least fix the XSL issue.

This problem is in no way related to symfonycasts/verify-email-bundle - just read the message: you are requiring doctrine/doctrine-migrations-bundle in your configuration, and you are using PHP 8. This Doctrine bundle has not been made compatible with PHP 8 yet, as doctrine/migrations is not compatible with PHP 8.

You either need to remove these packages, or downgrade to PHP 7