I found a mistake in my master thesis's code I defended my master thesis couple months ago in a German University. It's a thesis in Computer Science. In my thesis I mainly implemented some machine learning methods and compared their performance. The implementations of the methods and making them available as open-source are considered one of the main contributions of my thesis. I published the source-code online on Google's Code.

However, recently I was browsing the source-code of two methods' implementation and I found two bugs. One of the bugs makes the results of one experiment useless since the method became simply wrong. 

Now I'm very worried about that and don't know what to do or what I must or have to do. (They're not going to take my certificate back, right?)

My questions:


Since one of the main contributions of the thesis is the release of the source-code, am I obligated to fix the bugs?
Am I required to keep my source-code online? In other words, can I now decide to take it down and not give it to anyone? I'm the only one who has a copy of the source-code. My professor never asked me to put the source-code on a CD-ROM and put it in the thesis. I also mention in my thesis the online repository for the code.
I had very difficult memories of academia and I was so relieved when I finished. I don't want to contact them again to tell them about the bugs. But am I obligated to do that? I just want to start a new life and never think again about the past.


I'm asking those questions just to know my rights and if I have any obligations. However, since I'm passionate about my thesis topic, I'm actually considering fixing the bugs but I'm not willing to contact my professor and tell him, simply because I just don't want to communicate with someone from the past and still feel that I'm still stuck with academia or have obligations toward them.

Nobody has used my code yet, so if I fix the bug then the person who will clone the project will get a correct version (hopefully! I mean every software is subject to bugs!).

Edit:

I was asked "obligated by whom?". Well what I'm thinking is that since one of the main contributions of my thesis is the source-code, and since my examiners passed my thesis because it has contributions, then I thought that I must have that source-code always available. It feels to me like a contract: 

Make contributions (source-code as the main contribution) -> thesis passed -> you get your degree.

Now revoke contribution -> thesis failed -> you don't deserve your degree.

Isn't it like that?
they're not gonna take my certificate back, right


No, your degree won't be revoked on the basis of an honest mistake.  (Revoking the degree would only make sense for serious fraud or misconduct.)


  Since one of the main contributions of the thesis is the release of the source-code, am I obligated to fix the bugs?


Obligated by whom?  There's certainly no legal obligation, but deliberately withholding knowledge from the rest of the world would be unpleasant and harmful.

If you know how to fix the bugs without much effort, then I'd recommend that you do so.  If you don't know how to fix them or it would take too much time, you could at least attach a note explaining the problem (for the benefit of anyone who wants to use the code in the future).


  Am I required to keep my source-code online? In other words, can I now decide to take it down and not give it to anyone?


Again, required by whom?  Nobody can punish you if you take it down, but going out of your way to deny access is at least unfriendly.  If your thesis said that the code would be publicly available, then changing your mind now would be unethical.


  I don't want to contact them again to tell them about the bugs. But am I obligated to do that?


Nobody can make you, but it would be nice.  Think about it this way: another student might begin a project related to your thesis.  If you don't tell your advisor that the results of one experiment were wrong, then this student might experience pain and wasted time that could have been avoided if they had known about the problem earlier.  You might not care about your advisor, but surely there's some value to preventing future students from suffering unnecessarily.

And what's the worst case scenario if you tell your advisor?  Maybe your advisor would insult you, in which case you can take some satisfaction in having behaved better than your advisor, but there's nothing he/she can do to disrupt your life now.

In response to the edit:


  Well what I'm thinking is that since one of the main contributions of my thesis is the source-code, and since my examiners passed my thesis because it has contributions, then I thought that I must have that source-code always available. It feels to me like a contract:


If you said in the thesis that the code would be available in a public repository, then you have an ethical obligation to keep it available.  But universities revoke degrees only very rarely and for exceptionally serious reasons, such as research fraud or cheating.  There's no way a university would even try to revoke your degree for taking down the source code.  (However, if you're still worried you could look up your university's procedures for revoking degrees or search online for degrees revoked in the past.)

I don't mean to encourage you to take the code down, and I don't think you should.  My point is that this is about doing what you feel is right (keeping promises, helping other people, contributing to the world's knowledge) rather than about what someone else might try to make you do.