Try to fix as in previous versions was

app.py

@@ -281,9 +281,16 @@ def _clean_history_for_display(history: list[dict[str, Any]]) -> list[dict[str,
                     for k, v in item.items():
                         if k == "_pil_image":
                             continue
-                        if k == "alt_text" and not isinstance(v, str):
+                        if k == "alt_text":
+                            # Ensure alt_text is a string
+                            if isinstance(v, str):
+                                cleaned_item[k] = v
+                            # Skip non-string alt_text values
                             continue
                         cleaned_item[k] = v
+                    # Ensure alt_text exists for image type
+                    if cleaned_item.get("type") == "image" and "alt_text" not in cleaned_item:
+                        cleaned_item["alt_text"] = "uploaded image"
                     cleaned_content.append(cleaned_item)
                 else:
                     cleaned_content.append(item)
@@ -294,9 +301,16 @@ def _clean_history_for_display(history: list[dict[str, Any]]) -> list[dict[str,
             for k, v in content.items():
                 if k == "_pil_image":
                     continue
-                if k == "alt_text" and not isinstance(v, str):
+                if k == "alt_text":
+                    # Ensure alt_text is a string
+                    if isinstance(v, str):
+                        cleaned_item[k] = v
+                    # Skip non-string alt_text values
                     continue
                 cleaned_item[k] = v
+            # Ensure alt_text exists for image content
+            if "path" in cleaned_item and "alt_text" not in cleaned_item:
+                cleaned_item["alt_text"] = "uploaded image"
             cleaned_message["content"] = cleaned_item
         else:
             cleaned_message["content"] = content