How to fix a 'CSS-URL' error message resp. the redirection to a URL containing '____legacyBaseUrlTest____'?

Issue

When selecting a payment method and placing an order in my shop, it throws an error mentioning CSS-URL or redirects to a URL containing ____legacyBaseUrlTest____. For example:

http://yourshop.com/____legacyBaseUrlTest____

The issue occurs because the plugin is compatible to an older version of the API. However this API is not supported by newly activated merchant accounts.

Resolution

The issue lies with the authorization method used for the payment methods that is not supported in your account with your Payment Service Provider. To solve the issue you need to change the authorization method within the payment method configuration to `Widget Authorization'.