TL;DR
In this post, I will try to elaborate why is often expected from me as a tester to create meaningful application error messages.
So, you are using some web application, and you get something like this( thanks to Evil Tester):
And that error message does not tell you anything about your action or input. At least they put disclaimer: “That is all we know”.
While I am testing application, I find a lot of such not informative error messages. Why I find them and developers not? Because I know how to make reasonable scenarios that trigger those errors. And to come up with such scenarios and test data is not something of interest of regular developer. In my experience they find this very boring and not creative job. But I think that finding alternative flows by exploring api that you use is very creative and important job.
Developers just have different meaning for definition of DONE. Or they are just lazy.
First line of defense is that user will never do that. But you took BBST Bug advocacy, and you have already uncornered your test scenarios making it more probable in real life.
After I talk to project leader and provide him information about low quality error messages, I put extra work on my shoulders. Karlo, as you already found those error messages, you will create meaningful error messages.
The problem here is that I can only provide error messages for scenarios that I covered. But low level mechanics of the application, which includes inter module cooperation based on api contracts, this is developer responsibility.
by 
