diff --git a/aider/io.py b/aider/io.py
index 29ec13b58..b6b7d5820 100644
--- a/aider/io.py
+++ b/aider/io.py
@@ -319,8 +319,9 @@ class InputOutput:
             with open(str(filename), "r", encoding=self.encoding) as f:
                 return f.read()
         except OSError as err:
+            import traceback
             self.tool_error(f"{filename}: unable to read: {err}")
-            #ai print the trackback stack!
+            self.tool_error("Traceback:\n" + "".join(traceback.format_stack()))
             return
         except FileNotFoundError:
             self.tool_error(f"{filename}: file not found error")