Whelp, I avoided it as long as possible, but the time has finally come to make some changes to some ancient VB6 code. I'm a recent college grad so I was hoping to stay away from this code that is almost as old as I am.
The DLL is compiled in a local installation of VB6 and deployed via Component Services. That component is then called by VBScript in a Classic ASP application running on a windows 2003 Server.
I've tried just about everything to debug this code using the VB6 debugger, but I can't get it to work. I've compiled the DLL to the same location that Component Services has it deployed to (a random folder on a non-system drive), and set binary compatibility to that same DLL. Each class file has instancing set to MultiUse and MTSTransactionMode set to '1 - NoTransactions.' The component works fine until I attach the debugger, then I get 'ActiveX component can't create object' when trying to instantiate the object. If I detach the debugger, it works again.
I noticed that in Component Services when I attach the debugger, the DLL location changes to C:\Program Files\Microsoft Visual Studio\VB98\VB6DEBUG.DLL, which I assume is just VB6 intercepting calls to the component. When I detach the debugger, it changes back. I should also note that the component is configured to use a specific user identity separate from my logged-in user account, however everyone has been granted access to the component via a user role. The component activation type is also 'Server Application,' however setting it to 'Library Activate' doesn't seem to make a difference.
I've also tried using the VC++6 IDE, and VS2010, but had no luck. I was able to debug the dllhost.exe in VS2010 and was able to hit some breakpoints, but the symbols weren't loaded properly. I tried compiling the DLL with debugging symbols and loading those to the VS2010 environment via the Debug settings menu, however that didn't resolve the issue.
I also didn't find the component services JIT Debugger to be very useful. I'd much prefer to just be able to debug in VB6.
What amazes me most is that this code is thousands of lines and has been maintained without the use of any debugger whatsoever. My young, spoiled self isn't ready to accept that this code can't be debugged.