Use this module as a temporary solution to fix the invalid state change message in Magento 2, leading to orders not being created although the customer has payed for the order.
This module does not actualle fix the issue, but updates the quote according to the state that was requested. So if a logged in customer want's to place an order based on a quote for a guest customer, this module converts the quote to the logged in customer.
This might involve in security isues, so please concider before installing this plugin
To install this module use:
composer require gigadesign/module-magento2-fix-invalid-state-change
bin/magento setup:upgrade