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How does one debug something that can't be debugged?

by Seth » 2015-12-10 10:17

I'm proud to be a good debugger, but I'm almost at a loss here. How does one debug something that can not be debugged?

One of our customers has a problem with IE9 (so bonus: I had to use a VM for this debug). It will just hang on a particular page, always. When I say "hang" I mean that the Network tab in the tool developers do not show some of the first request will go out and finish (so no downloading of HTML), but after that nothing happened. The browser will not respond again and tabs that need to be firmly closed. Nothing will be given on the page, it's just spinning loading icon. the console does not show anything, using the Start Debugging button to break on the error had no effect, and using Profiler does nothing at all, it never showed data.

It is one of the clients of about 60 or more that use our applications, and they are the only one in which we look at this issue. This occurs on the registration page, and the field of their registration abnormally large or anything, they only have a few fields and it's not like they have a selection dropdown field to 1000 or whatever, the list of fields they are tame compared to other clients.

Usually requests for files Google Analytics is the last to appear in the network before the log tab stops responding, but it is not the only page where GA is loaded, it is also loaded on the login page that does not have a problem. Actually, it looks a little closer, I think the fact that the last request GA needed.

I hesitate to enter the URLs to the client's site here open, but if someone wants to send me a PM to see for myself then I would use my discretion. If not, I would welcome any suggestions on how I can trace a IE9 only issue where the only symptom that I can identify is a non-responsive browser.
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Joined: 2015-11-27 0:34

by Orlando » 2015-12-11 11:39

I only have a few suggestions are pretty obvious but, I guess, sometimes it helps to hear a second voice.

I assume you can replicate the problem on the version of IE9? (This negates my first thought, which is to check the plug-ins they have installed.) If so, then the problem does not recur with IE10 +? If not then you are probably looking for features that are not compatible with IE9, and may introduce a shim.

(Persuade them to update their browser is ideal, but it may not be acceptable, solution.)

If you can manage a full-test environment so you can selectively disable parts of the page to try to narrow down the problem. (I suspect that you may not be able to disable part of the live site.)

Anyway, good luck, and sorry if my advice is too obvious
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Joined: 2015-11-29 20:51

by Eliasl » 2015-12-12 17:08

I'm willing to help, I just need an old IE9 compatible operating system is loaded into the virtual machine. Download the operating system should not be long-term, and get it ...... If you have not figured out by then.
That's the reason why I do not want to do webdesign again: this time, you have to work with things like software Bootstrap, jQuery, server-side, etc. When everything works fine, but when there is a bug you have thousands of lines and / or thousands of files that you know nothing about to examine, with sometimes no clue where to start. And it is unpredictable: how you can estimate the cost of future problems, especially when the client urge you to keep the price as low as possible?
I've decided not so long to do only the things the client side because I do not want to be responsible for security issues or compatibility when I use software like Prestashop on the server side (how can you tell whether it vulnerable? How can you tell if a module will not corrupt the database or if the update will not damage the features?) and I'm considering stopping to do things the client side as well for the same reason. As a graphic designer I'm not used to seeing people come back to me and said "do not work", "some users complained that [...]", etc. but as a developer it happens too often.
I had the same problem with Microsoft Word once: the client wanted me to design templates for Word documents. What can you do when he comes back to you a month later because the font is changed when he tried to save documents as PDF or her printer to add a large margin on the one hand, or he did not understand how to use paragraph styles correctly and have messed up everything? Are you going to go to his office to see what happens? If it's big clients ... yes. And it's hard to charge for it because he thought it was your fault: "Your template does not work" he said.
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