When trying to edit an item in data repository, the opening popup requires an additional login with the following message provided.
Magnolia requires that requests include the http 'request' header. Please ensure that your browser or your company internet proxy do not modify the http 'request' header when accessing Magnolia.
Attention: the browser URL is not the standard login address, logging in with this URL may change data. Go to standard address (Change no data)
When switching back to version 4.5.17 same action does not lead to that behavior.
System is in both cases a dev system with no proxy or anything else in between