I actually don't see any issue that isn't simply a matter of money. Everything they list that's an issue seems to revolve around the fact that the employees with domain knowledge for the system have left the company. Reach out to them and hire them on as contractors. If they left under bad terms because the business was a bunch of dicks, expect to pay 10x market rate. If this is truly "fix this or the business is out…
It's slightly more complicated than that, depending on how much time has passed since the creators of the system left, but you're correct in general. Usually, since admitting that they were stupid to let all the knowledge of the system walk out the door requires more emotional and intellectual flexibility than managers who let this sort of thing happen possess, the biggest obstacle isn't even the money... it's gettin…
> The company that built this ERP solution went bankrupt 6 years ago, and we don't have the source code. It uses PostgreSQL and MySQL, and also has a built-in key-value database for which none of us has any credentials. We don't have the source code for this software (it's built in C and delivered to us as compiled packages..).
Sounds like finding their old employees wouldn't help. They need to find old employees of the company that wrote the system and hope they kept a copy of the source code.