Changes resume_from_checkpoint warning to error (#7075)

Co-authored-by: thomas chaton <[email protected]>
Co-authored-by: Carlos Mocholí <[email protected]>

Author: 3 people

pytorch_lightning/trainer/connectors/checkpoint_connector.py

@@ -87,8 +87,9 @@ def restore(self, checkpoint_path: str, on_gpu: bool) -> bool:
         # Try to read the checkpoint file at `checkpoint_path`. If not exist, do not restore checkpoint.
         fs = get_filesystem(checkpoint_path)
         if not fs.exists(checkpoint_path):
-            rank_zero_warn("No checkpoint file exists at `resume_from_checkpoint`. Start from scratch")
-            return False
+            raise FileNotFoundError(
+                f"Checkpoint at {checkpoint_path} not found. Aborting training."
+            )
 
         checkpoint, load_optimizer_states = self.trainer.training_type_plugin.restore_model_state_from_ckpt_path(
             checkpoint_path, map_location=lambda storage, loc: storage

tests/models/test_restore.py

@@ -148,7 +148,8 @@ def test_try_resume_from_non_existing_checkpoint(tmpdir):
     trainer.fit(model, datamodule=dm)
     # `True` if resume/restore successfully else `False`
     assert trainer.checkpoint_connector.restore(str(tmpdir / "last.ckpt"), trainer.on_gpu)
-    assert not trainer.checkpoint_connector.restore(str(tmpdir / "last_non_existing.ckpt"), trainer.on_gpu)
+    with pytest.raises(FileNotFoundError, match="Aborting training"):
+        trainer.checkpoint_connector.restore(str(tmpdir / "last_non_existing.ckpt"), trainer.on_gpu)
 
 
 class CaptureCallbacksBeforeTraining(Callback):