Fix #1260

worldedit-core/src/main/java/com/sk89q/worldedit/LocalSession.java

@@ -838,6 +838,17 @@ public class LocalSession implements TextureHolder {
         }
         setClipboard(multi);
     }
+
+    /**
+     * Ensure the player's clipboard is closed. (will only do something with clipboard-on-disk)
+     */
+    public void closeClipboard() {
+        synchronized (clipboardLock) {
+            if (this.clipboard != null) {
+                this.clipboard.close();
+            }
+        }
+    }
     //FAWE end
 
     /**

worldedit-core/src/main/java/com/sk89q/worldedit/command/ClipboardCommands.java

@@ -139,7 +139,7 @@ public class ClipboardCommands {
         }
         session.setClipboard(null);
 
-        Clipboard clipboard = new BlockArrayClipboard(region, actor.getUniqueId());
+        try (Clipboard clipboard = new BlockArrayClipboard(region, actor.getUniqueId())) {
 
             clipboard.setOrigin(centerClipboard ? region.getCenter().toBlockPoint() : session.getPlacementPosition(actor));
             ForwardExtentCopy copy = new ForwardExtentCopy(editSession, region, clipboard, region.getMinimumPoint());
@@ -170,6 +170,7 @@ public class ClipboardCommands {
             session.setClipboard(new ClipboardHolder(clipboard));
 
             copy.getStatusMessages().forEach(actor::print);
+        }
         //FAWE end
     }
 

worldedit-core/src/main/java/com/sk89q/worldedit/entity/Player.java

@@ -391,7 +391,7 @@ public interface Player extends Entity, Actor {
      */
     default void unregister() {
         cancel(true);
-        getSession().setClipboard(null);
+        getSession().closeClipboard();
         if (Settings.IMP.HISTORY.DELETE_ON_LOGOUT) {
             getSession().clearHistory();
         }