ultralytics 8.2.81 fix HUB missing 'best.pt' resumed checkpoint upload (#15754)

ultralytics/__init__.py

@@ -1,6 +1,6 @@
 # Ultralytics YOLO 🚀, AGPL-3.0 license
 
-__version__ = "8.2.80"
+__version__ = "8.2.81"
 
 import os
 

ultralytics/hub/session.py

@@ -1,5 +1,6 @@
 # Ultralytics YOLO 🚀, AGPL-3.0 license
 
+import shutil
 import threading
 import time
 from http import HTTPStatus
@@ -344,23 +345,34 @@ class HUBTrainingSession:
             map (float): Mean average precision of the model.
             final (bool): Indicates if the model is the final model after training.
         """
-        if Path(weights).is_file():
-            progress_total = Path(weights).stat().st_size if final else None  # Only show progress if final
+        weights = Path(weights)
+        if not weights.is_file():
+            last = weights.with_name("last" + weights.suffix)
+            if final and last.is_file():
+                LOGGER.warning(
+                    f"{PREFIX} ARNING ⚠️ Model 'best.pt' not found, copying 'last.pt' to 'best.pt' and uploading. "
+                    "This often happens when resuming training in transient environments like Google Colab. "
+                    "For more reliable training, consider using Ultralytics HUB Cloud. "
+                    "Learn more at https://docs.ultralytics.com/hub/cloud-training/."
+                )
+                shutil.copy(last, weights)  # copy last.pt to best.pt
+            else:
+                LOGGER.warning(f"{PREFIX} WARNING ⚠️ Model upload issue. Missing model {weights}.")
+                return
+
         self.request_queue(
             self.model.upload_model,
             epoch=epoch,
-                weights=weights,
+            weights=str(weights),
             is_best=is_best,
             map=map,
             final=final,
             retry=10,
             timeout=3600,
             thread=not final,
-                progress_total=progress_total,
+            progress_total=weights.stat().st_size if final else None,  # only show progress if final
             stream_response=True,
         )
-        else:
-            LOGGER.warning(f"{PREFIX}WARNING ⚠️ Model upload issue. Missing model {weights}.")
 
     @staticmethod
     def _show_upload_progress(content_length: int, response: requests.Response) -> None: