Sorry, this is more of a complaint than anything else.
I've spent the better part of two days troubleshooting a
ValidationException in a CloudFormation stack that is nearly 100% devoid of any substance.
I've worked in systems with particularly awful error messages in the past (I'm talking about you, Win32 API, and ORA-NNNNN), but most of those were merely annoying and time-consuming. You could still trace, you could still look up the error and get something that would point you in a direction.
400 as a status code, and a brief text blurb saying which service threw the message is entirely useless.
I'm just saying, could the biggest player in cloud computing please step up their error message game? This is just silly, and it's costing me days of my life that I can't get back.