I spotted a bug today in a web application that I develop and maintain for a client. I let the client know that I had spotted a problem and after a short time I fixed it and reported back the full details to them.

In cases like these do you always tell your client? Even though it would be possible to fix the problem and tell no one?

  • 2
    You used the words "formal methods". I do not think they mean what you think they mean. Inconceivable, I know, but I re-tagged the question.
    – user4051
    Mar 1, 2011 at 21:15
  • Thanks Graham, I wondered if that was a suitable tag. Didn't see 'bugs' in the list, sorry about that.
    – Gortron
    Mar 1, 2011 at 21:17

9 Answers 9



Assuming you're being paid to maintain it then definitely inform. The choice of where to inform them is a bit more subjective. If you notice a small issue and can immediately roll out a fix do so and tell them after the fact. For larger issues raise it to their attention, roll a fix, and then let them know when it's complete.

  • 5
    Another reason: we make mistakes. Perhaps you didn't fix it correctly, or an unforeseen side-effect occurred.
    – rlb.usa
    Mar 1, 2011 at 21:18

You should be asking your client before fixing the bug.

The client may decide that they want your precious time spent on other things and that they can either afford to live with the bug, or get someone else to fix it.

Fix it if they say to do so.

Regardless, seeing as you fixed it, you should definitely tell the client. They may have depended on the bug being there, already know about it and assigned someone to fix it already...

As for this being your code - disclosing the bug to client about it is the professional thing to do. If their business depends on your software, they would not appreciate not knowing about the bug. They may have it deployed in several locations and without your report would not know that they need to update all locations as soon as possible.

They will appreciate your honesty and professionalism more than worry about the bug (unless it cost them an arm and a leg already...).

  • Understood, though in this case the bug was potentially serious and so I doubt they'd depend on it and there wouldn't be anyone else around to fix it.
    – Gortron
    Mar 1, 2011 at 20:58
  • @Gorton - answer updated. If it was potentially serious all the more reason to tell them about it.
    – Oded
    Mar 1, 2011 at 20:59
  • I'm sure you could submit a patch, even before you ask. Then their developers can review and apply it if they want.
    – user4051
    Mar 1, 2011 at 21:14
  • +1 because depending on the bug, the client may have ended up relying on it. And they're paying you. We have some of those floating around and can't fix them because of that.
    – Izkata
    Apr 11, 2012 at 21:00

I think it highly depend on the customer.

Ask your customer his/her preferences

I would feel personaly annoyed to receive a notification each time someone is doing his job.

On the other hand, many clients will appreciate the feedback.

  • Good idea, I'll ask them what they would prefer, Thanks Pierre 303.
    – Gortron
    Mar 1, 2011 at 21:02

Yes. If you don't, and your bugfix causes some problem, you are in an extremely bad situation.

You might think: But my bugfix was clearly correct! No chance it causes problems! But... the bug you have fixed might have hidden another, possibly more critical bug. Before you fixed the bug, it ran into an error before it could do something stupid. Now...

Other reason to tell: Your client might have noticed the bug, but not reported it yet. If you fix it without telling, your client might be confused and frustrated, because he can't explain why the program behaves differently than yesterday.

If the client hasn't noticed the bug yet, and you tell him, he won't be offended, as long as you don't charge him for the bugfix.


Yes I think its good to inform the client anytime something like this happens. For one thing they might have already seen the bug and may not have informed you about it. Also it shows that you are conscientious about doing your job and may get you more work in the future, just based off of that. It also doesn't hurt to show them what they are paying you for in the first place.

  • Thanks for your answers, I was curious to see if other developers would do the same. Its possible a client could think less of the developer for writing that code in the first place.
    – Gortron
    Mar 1, 2011 at 20:57
  • Your right that is possible and if your client is like that, then I can see your dilemma. You may want to steer toward clients that will accept that human mistakes can be made. At least that would be my preference anyway. :-)
    – mwgriffith
    Mar 6, 2011 at 16:48


For the answers given, and for the fact that the client (although this is rarely the case in web development) might know about the bug, and for some reason they've decided not to fix it, but adjust the other part to it. I.e. they know about it, and you by trying to fix it are actually the one breaking the system.

Seen quite a few of cases of long-standing bugs that should not be touched! Life continued fine though.


I think it depends on the type of defect. If it's something that would be noticeable through normal front-end usage then the it would be beneficial to tell the client. At the very least they can re-test and make sure functionality is as they would expect. If the defect is in the guts of the system and would require technical knowledge to truly understand, you may want to fix it and move on. If the user is business, rather than technically, oriented it may just cause confusion and further concern from lack of truly understanding the issue.

Take something like World of Warcraft. In tehe patch notes, Blizzard will list any gameplay related fixes they have made. Unless I'm mistaken they wont post a list of defects affecting behind the scenes/engine level funtionality that they may have taken care of.


If your question was "Should I try to hide the fact the bug ever existed?", if you're working for a client for whom hiding the truth is a good idea, maybe you should discontinue working for that client and find another client.


Depends on your relationship with the client and the nature of your employment: Are you are contractor being paid by the hour or an employee. If you're billing by the hour, you must give account for your time.

Is the client tech savvy or not? Do they understand that 'bugs happen' and don't make you a bad programmer? Will they look upon you more favorably if you tell them you found it and fixed it, or hold it against you?

Sometimes when dealing the clients, 'What they don't know, won't hurt them'.

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