ServerApplication + poco_assert (_pInstance == 0);

[iquestcorp]

Resolved: I had two subclasses of ServerApplication that were being allocated recursively.

[Sqarzz]

I'm actually also having an error that resembles your issue.
poco_assert (!_pStream) gives me the error.
Do you have an idea what the assert function actually does/is for?
My first year of c++ and haven't seen anything like it before.

[fbraem]

poco_assert (!_pStream) gives me the error.

It means that _pStream is pointing to NULL. Probably the stream is closed and you are still trying to use it ...