I know this is a common question asked here. But I am not understanding why my Question was downvoted. Is it because its stupid or not well written or something else. Shouldn't there be a system for the user who asked the question to know why his question was downvoted so that he can improve his question, which should improve the overall quality of the site. Or is there some method to achive this?
I can tell you, someone also voted to close the question as
unclear what you are asking, this is likely the reason you were downvoted too, but I can't tell for sure, I do agree that if someone thinks the question is unclear they should really say why.
To me there is nothing wrong with the question, it is a common type of question and contains all output and errors etc.
Unfortunately, sometimes people get things wrong, spend some time in review and you will see what I mean. Also there is nothing anyone can do about a single vote but don't worrie about it, one vote is negligible.
Shouldn't there be a system for the user who asked the question to know why his question was downvoted
This is an often discussed point on meta but consensus is that users should have the right to not have to explain why they voted on a Q/A because a lot of users respond with hostility and, of course, users have the right to not have to deal with that.
Check some of these post to see the discussion on voting
There are many more in this Google search, I hope this helps to explain the situation a bit for you, even if there is nothing we can do.
Your question lack basic information that would allow others to answer it successfully. Check What information do I need to solve an APT dependency issue?, edit your question to add more information.