diff --git a/ppgan/models/msvsr_model.py b/ppgan/models/msvsr_model.py
index 1c394ef3f6fd7df8de75ad9978c335e41504f118..04bdfb467bb38b1aadd0183c37234f7632b1e539 100644
--- a/ppgan/models/msvsr_model.py
+++ b/ppgan/models/msvsr_model.py
@@ -118,7 +118,7 @@ class MultiStageVSRModel(BaseSRModel):
                     net.find_unused_parameters = False
 
         # put loss computation in amp context
-        with paddle.amp.auto_cast(enable=True, level=amp_level):
+        with paddle.amp.auto_cast(enable=True, custom_black_list={'sqrt','scale'}, level=amp_level):
             output = self.nets['generator'](self.lq)
             if isinstance(output, (list, tuple)):
                 out_stage2, output = output
diff --git a/requirements.txt b/requirements.txt
index a8dda255ad9ca47567aef5cd1aa5e20281b7a495..8b072c66e7e2d8c2957a823680e55b7838bebbf2 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,7 +2,7 @@ tqdm
 PyYAML>=5.1
 scikit-image>=0.14.0
 scipy>=1.1.0
-opencv-python
+opencv-python <= 4.6.0
 imageio==2.9.0
 imageio-ffmpeg
 librosa==0.8.1