Usually, IllegalStateException is used to indicate that “a method has been invoked at an illegal or inappropriate time.” However, this doesn’t look like a particularly typical use of it.
The code you’ve linked to shows that it can be thrown within that code at line 259 – but only after dumping a SQLException to standard output.
We can’t tell what’s wrong just from that exception – and better code would have used the original SQLException as a “cause” exception (or just let the original exception propagate up the stack) – but you should be able to see more details on standard output. Look at that information, and you should be able to see what caused the exception, and fix it.