We have run into a problem in our production system. Luckily, this is a pretty obvious case of misdirection.

Take a look at the stack trace that we have discovered:

The interesting bit is that this is an “impossible” error. In fact, this is the first time that we have actually seen this error ever.

But looking at the stack trace tells us pretty much everything. The error happens in Dispose, but that one is called from the constructor. Because we are using native code, we need to make sure that an exception in the ctor will properly dispose all unmanaged resources.

The code looks like this:

And here we can see the probable cause for the error. We try to open a transaction, then an exception happens, and the Dispose is called, but it isn’t ready to handle this scenario, so throws.

The original exception is masked, and you have a hard debug scenario.