I have just tried "abandontransaction " and I get this:
"Transaction not eligible for abandonment (code -5)"
What does it mean?
Don't know what it mean but try using zapwalletexes instead. Refer to
this post on how to do it for windows. The OP on that thread got the same message too.
Make sure you close bitcoin core before you do that. And backup your wallet.dat just in case.