Index: /trunk/src/org/openstreetmap/josm/tools/PlatformHook.java
===================================================================
--- /trunk/src/org/openstreetmap/josm/tools/PlatformHook.java	(revision 15921)
+++ /trunk/src/org/openstreetmap/josm/tools/PlatformHook.java	(revision 15922)
@@ -144,5 +144,6 @@
     default boolean isHighDpiDisplay() {
         // https://stackoverflow.com/a/49770313
-        return !GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration()
+        return !GraphicsEnvironment.isHeadless() &&
+                !GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration()
                 .getDefaultTransform().isIdentity();
     }