diff --git a/starpunk/media.py b/starpunk/media.py
index c4a6401..216ccee 100644
--- a/starpunk/media.py
+++ b/starpunk/media.py
@@ -121,7 +121,16 @@ def validate_image(file_data: bytes, filename: str) -> Tuple[bytes, str, int, in
                 )
                 # Mark as HEIF so conversion happens below
                 img.format = 'HEIF'
-            except Exception:
+            except Exception as heic_error:
+                # Log the magic bytes for debugging (if in app context)
+                try:
+                    magic = file_data[:12].hex() if len(file_data) >= 12 else file_data.hex()
+                    current_app.logger.warning(
+                        f'Media upload failed both Pillow and HEIC: filename="{filename}", '
+                        f'magic_bytes={magic}, pillow_error="{e}", heic_error="{heic_error}"'
+                    )
+                except RuntimeError:
+                    pass  # Outside app context (e.g., tests)
                 raise ValueError(f"Invalid or corrupted image: {e}")
         else:
             raise ValueError(f"Invalid or corrupted image: {e}")