Somewhat improved the bad backup error message.

src/SnapshotRestore.java

@@ -49,6 +49,10 @@ public class SnapshotRestore {
      * Count of the number of chunks that could be loaded for other reasons.
      */
     private ArrayList<Vector2D> errorChunks;
+    /**
+     * Last error message.
+     */
+    private String lastErrorMessage;
 
     /**
      * Construct the snapshot restore operation.
@@ -153,8 +157,10 @@ public class SnapshotRestore {
                 missingChunks.add(chunkPos);
             } catch (DataException de) {
                 errorChunks.add(chunkPos);
+                lastErrorMessage = de.getMessage();
             } catch (IOException ioe) {
                 errorChunks.add(chunkPos);
+                lastErrorMessage = ioe.getMessage();
             }
         }
     }
@@ -188,4 +194,11 @@ public class SnapshotRestore {
     public boolean hadTotalFailure() {
         return missingChunks.size() + errorChunks.size() == getChunksAffected();
     }
+
+    /**
+     * @return the lastErrorMessage
+     */
+    public String getLastErrorMessage() {
+        return lastErrorMessage;
+    }
 }

src/WorldEditListener.java

@@ -1353,7 +1353,13 @@ public class WorldEditListener extends PluginListener {
                 restore.restore(editSession);
 
                 if (restore.hadTotalFailure()) {
-                    player.printError("No blocks could be restored. (Bad backup?)");
+                    String error = restore.getLastErrorMessage();
+                    if (error != null) {
+                        player.printError("Errors prevented any blocks from being restored.");
+                        player.printError("Last error: " + error);
+                    } else {
+                        player.printError("No chunks could be loaded. (Bad archive?)");
+                    }
                 } else {
                     player.print(String.format("Restored; %d "
                             + "missing chunks and %d other errors.",