diff --git a/codes/data/util.py b/codes/data/util.py
index 516c6ae9..181896b1 100644
--- a/codes/data/util.py
+++ b/codes/data/util.py
@@ -79,6 +79,8 @@ def read_img(env, path, size=None):
         img = cv2.imread(path, cv2.IMREAD_UNCHANGED)
     else:
         img = _read_img_lmdb(env, path, size)
+    if img is None:
+        print("Image error: %s" % (path,))
     img = img.astype(np.float32) / 255.
     if img.ndim == 2:
         img = np.expand_dims(img, axis=2)