diff --git a/CHANGELOG.md b/CHANGELOG.md
index 37ed6891..dc88bb42 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,7 @@ FlatLaf Change Log
     when resizing window. (issue #907)
 - Popup: On Windows 10, fixed misplaced popup drop shadow. (issue #911;
   regression in 3.5)
+- Popup: Fixed NPE if `GraphicsConfiguration` is `null` on Windows. (issue #921)
 - Theme Editor: Fixed using color picker on secondary screen.
 
 
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatNativeLinuxLibrary.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatNativeLinuxLibrary.java
index 8f0ee8b3..952d0ece 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatNativeLinuxLibrary.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatNativeLinuxLibrary.java
@@ -16,6 +16,7 @@
 
 package com.formdev.flatlaf.ui;
 
+import java.awt.GraphicsConfiguration;
 import java.awt.Point;
 import java.awt.Toolkit;
 import java.awt.Window;
@@ -96,7 +97,11 @@ class FlatNativeLinuxLibrary
 	}
 
 	private static Point scale( Window window, Point pt ) {
-		AffineTransform transform = window.getGraphicsConfiguration().getDefaultTransform();
+		GraphicsConfiguration gc = window.getGraphicsConfiguration();
+		if( gc == null )
+			return pt;
+
+		AffineTransform transform = gc.getDefaultTransform();
 		int x = (int) Math.round( pt.x * transform.getScaleX() );
 		int y = (int) Math.round( pt.y * transform.getScaleY() );
 		return new Point( x, y );
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupFactory.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupFactory.java
index bb362106..c5621132 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupFactory.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupFactory.java
@@ -138,7 +138,8 @@ public class FlatPopupFactory
 
 		// create drop shadow popup
 		Popup popupForScreenOfOwner = getPopupForScreenOfOwner( owner, contents, x, y, forceHeavyWeight );
-		return owner.getGraphicsConfiguration().isTranslucencyCapable()
+		GraphicsConfiguration gc = owner.getGraphicsConfiguration();
+		return (gc != null && gc.isTranslucencyCapable())
 			? new DropShadowPopup( popupForScreenOfOwner, owner, contents )
 			: new NonFlashingPopup( popupForScreenOfOwner, owner, contents );
 	}
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupMenuUI.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupMenuUI.java
index f6d3af4f..69fc6ec4 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupMenuUI.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupMenuUI.java
@@ -239,11 +239,13 @@ public class FlatPopupMenuUI
 		if( gc == null && popupMenu.getInvoker() != null )
 			gc = popupMenu.getInvoker().getGraphicsConfiguration();
 
-		// compute screen height
+		if( gc == null )
+			return new Rectangle( Toolkit.getDefaultToolkit().getScreenSize() );
+
+		// compute screen bounds
 		// (always subtract screen insets because there is no API to detect whether
 		// the popup can overlap the taskbar; see JPopupMenu.canPopupOverlapTaskBar())
-		Toolkit toolkit = Toolkit.getDefaultToolkit();
-		Rectangle screenBounds = (gc != null) ? gc.getBounds() : new Rectangle( toolkit.getScreenSize() );
+		Rectangle screenBounds = gc.getBounds();
 		Insets screenInsets = Toolkit.getDefaultToolkit().getScreenInsets( gc );
 		return FlatUIUtils.subtractInsets( screenBounds, screenInsets );
 	}
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTitlePane.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTitlePane.java
index 42695588..6a9d9983 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTitlePane.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatTitlePane.java
@@ -824,7 +824,8 @@ public class FlatTitlePane
 		Rectangle oldMaximizedBounds = frame.getMaximizedBounds();
 		if( !hasNativeCustomDecoration() &&
 			(oldMaximizedBounds == null ||
-			 Objects.equals( oldMaximizedBounds, rootPane.getClientProperty( "_flatlaf.maximizedBounds" ) )) )
+			 Objects.equals( oldMaximizedBounds, rootPane.getClientProperty( "_flatlaf.maximizedBounds" ) )) &&
+			window.getGraphicsConfiguration() != null )
 		{
 			GraphicsConfiguration gc = window.getGraphicsConfiguration();
 
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatWindowResizer.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatWindowResizer.java
index 35fbb5e7..c466ecf8 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatWindowResizer.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatWindowResizer.java
@@ -329,20 +329,17 @@ public abstract class FlatWindowResizer
 
 		@Override
 		protected boolean limitToParentBounds() {
-			return limitResizeToScreenBounds && window != null;
+			return limitResizeToScreenBounds && window != null && window.getGraphicsConfiguration() != null;
 		}
 
 		@Override
 		protected Rectangle getParentBounds() {
-			if( limitResizeToScreenBounds && window != null ) {
-				GraphicsConfiguration gc = window.getGraphicsConfiguration();
-				Rectangle bounds = gc.getBounds();
-				Insets insets = window.getToolkit().getScreenInsets( gc );
-				return new Rectangle( bounds.x + insets.left, bounds.y + insets.top,
-					bounds.width - insets.left - insets.right,
-					bounds.height - insets.top - insets.bottom );
-			}
-			return null;
+			GraphicsConfiguration gc = window.getGraphicsConfiguration();
+			Rectangle bounds = gc.getBounds();
+			Insets insets = window.getToolkit().getScreenInsets( gc );
+			return new Rectangle( bounds.x + insets.left, bounds.y + insets.top,
+				bounds.width - insets.left - insets.right,
+				bounds.height - insets.top - insets.bottom );
 		}
 
 		@Override
diff --git a/flatlaf-extras/src/main/java/com/formdev/flatlaf/extras/FlatInspector.java b/flatlaf-extras/src/main/java/com/formdev/flatlaf/extras/FlatInspector.java
index 29f91e67..4f4dcc0f 100644
--- a/flatlaf-extras/src/main/java/com/formdev/flatlaf/extras/FlatInspector.java
+++ b/flatlaf-extras/src/main/java/com/formdev/flatlaf/extras/FlatInspector.java
@@ -24,6 +24,7 @@ import java.awt.Dimension;
 import java.awt.EventQueue;
 import java.awt.Font;
 import java.awt.Graphics;
+import java.awt.GraphicsConfiguration;
 import java.awt.Insets;
 import java.awt.KeyboardFocusManager;
 import java.awt.LayoutManager;
@@ -450,15 +451,18 @@ public class FlatInspector
 		Dimension size = tip.getPreferredSize();
 
 		// position the tip in the visible area
-		Rectangle visibleRect = rootPane.getGraphicsConfiguration().getBounds();
-		if( tx + size.width > visibleRect.x + visibleRect.width )
-			tx -= size.width + UIScale.scale( 16 );
-		if( ty + size.height > visibleRect.y + visibleRect.height )
-			ty -= size.height + UIScale.scale( 32 );
-		if( tx < visibleRect.x )
-			tx = visibleRect.x;
-		if( ty < visibleRect.y )
-			ty = visibleRect.y;
+		GraphicsConfiguration gc = rootPane.getGraphicsConfiguration();
+		if( gc != null ) {
+			Rectangle visibleRect = gc.getBounds();
+			if( tx + size.width > visibleRect.x + visibleRect.width )
+				tx -= size.width + UIScale.scale( 16 );
+			if( ty + size.height > visibleRect.y + visibleRect.height )
+				ty -= size.height + UIScale.scale( 32 );
+			if( tx < visibleRect.x )
+				tx = visibleRect.x;
+			if( ty < visibleRect.y )
+				ty = visibleRect.y;
+		}
 
 		PopupFactory popupFactory = PopupFactory.getSharedInstance();
 		popup = popupFactory.getPopup( c, tip, tx, ty );