ADDITIONAL SYSTEM INFORMATION :
Behaviour was as expected in 17.0.11 and 21.0.3, but changed dramatically in 17.0.12 and 21.0.4.
Context is a web application (Java WAR file) running as a service in Tomcat 9 and 10 under Windows.

A DESCRIPTION OF THE PROBLEM :
We experience basically the same issue as reported in JDK-8336862

In the upgrade from 17.0.11 to 17.0.12 and at the same time between 21.0.3 and 21.0.4 there was a big change in the behaviour of the Swing/AWT subsystem.

We have a server side application that uses Swing and AWT components and subsystems to perform various graphical rendering operations.

We run as a web application (WAR file) under Tomcat 9 and 10 and we require the JDK to run with headless mode OFF. So java.awt.headless is always set to false. Since the update to 17.0.12 and 21.0.4 we get the same message as reported in the issue: "java.awt.AWTError: no screen devices".

We require this Swing/AWT functionality to work on Windows when running as a service.

REGRESSION : Last worked in version 21