Sentinel-2 Pre-Processing Graph Error

I am using SNAP 7 and Python 3.6.3 for Sen-ET. I could only configure python 3.6 with SNAP 7. However, when I am trying to run the sentinel-2 preprocessing graph it is showing the following error:
Expression is invalid. Undefined symbol ‘quality_scene_classification’
Can someone please help me? How can I solve this issue.
Thank you.

Is this part of the SEN-ET?

Yes this is part of the Sen-ET

Have you checked that the MSI L2 product contains the quality_scene_classification file? It should be in the quality folder.

Hi, I was having the same problem. Now I checked my product and I have the quality_scene_classification file in quality folder. But it still says invalid expression. How can I solve this?

Be sure that the “Read” is taking the right product, if you have several open at the same time. I cannot tell more without screenshots or log files.

When I click on the edit expression option it shows no files selected in the data sources. I think that is the problem. And i cannot check the options for showing bands or masks.

Could you show me the read label?