Debugging ‘Multiple-step operation generated errors’ errors in VB6 and SQL 2005

I just blogged about CSFBL moving to its new server. All was going well, until I tried to kick off the sim engine, a big part of which is written in Visual Basic 6.0 (cringe, I know, but who has time to rewrite legacy code?).

The sim engine is implemented as a DLL which gets invoked via COM. This part works fine; the DLL is activated, properties are sent to it, and it runs… then crashes, with the following obscure error:

Error Number: -2147217887
Description: Multiple-step operation generated errors. Check each status value.

I searched, and searched… nothing. I recompiled, and checked settings… nothing. I prayed, and finally found this post:

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