@houda yes if you remove all files containing the date of this ifg in the stamps_export folder this date will not be processed in mt_prep_snap and i should solve the error.
you could also try to reprocess that date and maybe that will fix the file, common problems are:
- accidentally putting a descending file in your ascending file (or vice versa)
- accidentally split the wrong subswath
- accidentally put file of different path/frame in the project folder
i have also had cases where the Sentinel 1 file was just corrupt 
but just removing the date will solve your problem.