diff --git a/api/onnx_web/chain/source_s3.py b/api/onnx_web/chain/source_s3.py
index 539f07df..7e5666d2 100644
--- a/api/onnx_web/chain/source_s3.py
+++ b/api/onnx_web/chain/source_s3.py
@@ -49,6 +49,7 @@ class SourceS3Stage(BaseStage):
             except Exception:
                 logger.exception("error loading image from S3")
 
+        # TODO: attempt to load metadata from s3 or load it from the image itself (exif data)
         return StageResult(outputs)
 
     def outputs(
diff --git a/api/onnx_web/chain/upscale_resrgan.py b/api/onnx_web/chain/upscale_resrgan.py
index 53afce2a..5e0799c1 100644
--- a/api/onnx_web/chain/upscale_resrgan.py
+++ b/api/onnx_web/chain/upscale_resrgan.py
@@ -48,10 +48,10 @@ class UpscaleRealESRGANStage(BaseStage):
                 self.model = model
                 self.device = device
 
-        model_file = "%s.%s" % (params.upscale_model, params.format)
+        model_file = f"{params.upscale_model}.onnx"
         model_path = path.join(server.model_path, model_file)
 
-        cache_key = (model_path, params.format)
+        cache_key = (model_path, params.scale)
         cache_pipe = server.cache.get(ModelTypes.upscaling, cache_key)
         if cache_pipe is not None:
             logger.info("reusing existing Real ESRGAN pipeline")
diff --git a/api/onnx_web/params.py b/api/onnx_web/params.py
index b8dc3049..8e8c593a 100644
--- a/api/onnx_web/params.py
+++ b/api/onnx_web/params.py
@@ -400,7 +400,6 @@ class UpscaleParams:
         faces=True,
         face_outscale: int = 1,
         face_strength: float = 0.5,
-        format: Literal["onnx", "pth"] = "onnx",  # TODO: deprecated, remove
         outscale: int = 1,
         scale: int = 4,
         pre_pad: int = 0,
@@ -416,7 +415,6 @@ class UpscaleParams:
         self.faces = faces
         self.face_outscale = face_outscale
         self.face_strength = face_strength
-        self.format = format
         self.outscale = outscale
         self.pre_pad = pre_pad
         self.scale = scale
@@ -432,7 +430,6 @@ class UpscaleParams:
             faces=self.faces,
             face_outscale=self.face_outscale,
             face_strength=self.face_strength,
-            format=self.format,
             outscale=scale,
             scale=scale,
             pre_pad=self.pre_pad,
@@ -459,7 +456,6 @@ class UpscaleParams:
             "faces": self.faces,
             "face_outscale": self.face_outscale,
             "face_strength": self.face_strength,
-            "format": self.format,
             "outscale": self.outscale,
             "pre_pad": self.pre_pad,
             "scale": self.scale,
@@ -476,7 +472,6 @@ class UpscaleParams:
             kwargs.get("faces", self.faces),
             kwargs.get("face_outscale", self.face_outscale),
             kwargs.get("face_strength", self.face_strength),
-            kwargs.get("format", self.format),
             kwargs.get("outscale", self.outscale),
             kwargs.get("scale", self.scale),
             kwargs.get("pre_pad", self.pre_pad),
diff --git a/api/onnx_web/server/params.py b/api/onnx_web/server/params.py
index b19f541a..0b4a11cb 100644
--- a/api/onnx_web/server/params.py
+++ b/api/onnx_web/server/params.py
@@ -289,7 +289,6 @@ def build_upscale(
         faces=faces,
         face_outscale=face_outscale,
         face_strength=face_strength,
-        format="onnx",
         outscale=outscale,
         scale=scale,
         upscale_order=upscale_order,