Error with FMASK with Sentinel-2 L1C images


I did not know where to post my message. Sorry if I am at the wrong place.

I have an issue using python FMASK (0.4-3) with S2-L1C products. I use GDAL-2.1.3 and rios-1.4.3; I tried with several images and I still get the same error.

Can you help me please?

Thank you by advance.