Debug Assertion Failed: C++ exception in a C# application?

Question

I have been managing and updating a particular application. It is old and I am not the original developer. It's suffered through several debugging sessions over the years among other small patches.

It has been running stable for the last couple of months, but then an exception occurred that seems odd to me. Since this only happens on the server ( it is a server application. ) in release mode.

The application is written in C#, is managed in Visual Studio 2012 Professional and is released to be explicitly 32-bit .NET 3.5 since the server is unfortunately running Windows 2003. (I have tried to convince them to update so I can update the application to .NET 4.5. But alas.)

So I am getting a C++ Debug message. See the screenshot below. It occurs in a file named vsprintf.c I am guessing on line 91. The only message that gives me any hint is format != NULL.

This confuses me however. What can possibly cause this? What steps can I best take to debug in a situation like this? What is "vsprintf.c"?

Edit: I managed to find something in eventviewer. I will continue to research this in the meanwhile.

Sincerely,

me.

Answer 1

This is an assertion failure, ie an assumtion that a function you are calling makes is not met, in this case that a pointer is not null. From the looks of it, its a format string. Are you using format strings directly? If so, look there. If not, this is probably a memory leak problem, followed by an out-of-memory malfunction.

Answer 2

vsprintf calls can be caused by sprintf and other derivates, you should maybe check all these calls. (This can also be methods of string classes, as I saw in the VCL).

If the bug isn't caused by one of the libraries you use, then there should be a NULL (or 0) in the format string parameter, which is mostly the last before the ... in the prototype.

If you are familiar with regular expressions, this may help a lot when looking for patterns.