No, you won’t be promoted to next year in DU SOL, if you fail in all subjects. You will have to repeat that year. You will be promoted to the next year if you fail in less than 50% of the examinations. You will have to take the back examination for those subjects next year.
After reading the reviews about this online, I can say that if you fail the majority of the subjects, you will not be promoted at all.
Students failing less than 50% of the exams, for example, you have failed in 8 subjects but passed in 5, then there is a chance of you getting promoted. Though you will have to give the exams in the following semester, failing which you will get promoted but have to repeat the exams again every semester.
If you fail in one or more subjects in your last semester, then you have to wait a year-long for the next exam, after which you will receive your degree.