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

@@ -139,37 +139,38 @@ 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());
-        copy.setCopyingEntities(copyEntities);
-        copy.setCopyingBiomes(copyBiomes);
+            clipboard.setOrigin(centerClipboard ? region.getCenter().toBlockPoint() : session.getPlacementPosition(actor));
+            ForwardExtentCopy copy = new ForwardExtentCopy(editSession, region, clipboard, region.getMinimumPoint());
+            copy.setCopyingEntities(copyEntities);
+            copy.setCopyingBiomes(copyBiomes);
 
-        Mask sourceMask = editSession.getSourceMask();
-        Region[] regions = editSession.getAllowedRegions();
-        Region allowedRegion;
-        if (regions == null || regions.length == 0) {
-            allowedRegion = new NullRegion();
-        } else {
-            allowedRegion = new RegionIntersection(regions);
+            Mask sourceMask = editSession.getSourceMask();
+            Region[] regions = editSession.getAllowedRegions();
+            Region allowedRegion;
+            if (regions == null || regions.length == 0) {
+                allowedRegion = new NullRegion();
+            } else {
+                allowedRegion = new RegionIntersection(regions);
+            }
+            final Mask firstSourceMask = mask != null ? mask : sourceMask;
+            final Mask finalMask = MaskIntersection.of(firstSourceMask, new RegionMask(allowedRegion)).optimize();
+            if (finalMask != Masks.alwaysTrue()) {
+                copy.setSourceMask(finalMask);
+            }
+            if (sourceMask != null) {
+                editSession.setSourceMask(null);
+                new MaskTraverser(sourceMask).reset(editSession);
+                editSession.setSourceMask(null);
+            }
+
+            Operations.completeLegacy(copy);
+            saveDiskClipboard(clipboard);
+            session.setClipboard(new ClipboardHolder(clipboard));
+
+            copy.getStatusMessages().forEach(actor::print);
         }
-        final Mask firstSourceMask = mask != null ? mask : sourceMask;
-        final Mask finalMask = MaskIntersection.of(firstSourceMask, new RegionMask(allowedRegion)).optimize();
-        if (finalMask != Masks.alwaysTrue()) {
-            copy.setSourceMask(finalMask);
-        }
-        if (sourceMask != null) {
-            editSession.setSourceMask(null);
-            new MaskTraverser(sourceMask).reset(editSession);
-            editSession.setSourceMask(null);
-        }
-
-        Operations.completeLegacy(copy);
-        saveDiskClipboard(clipboard);
-        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();
         }