There was never a bug here. The doc is quite explicit http://www.lmdb.tech/doc/group__mdb.html#ga73a5938ae4c3239ee11efa07eb22b882

After txn_abort the only valid call on a still-open cursor is cursor_renew, not cursor_close.

However you want to call it, are you open to improve this workflow?

API-wise, it would be so much simpler just to free a cursor after it became obsolete. It's counter-intuitive to open a new txn, renew the cursor, close the cursor, and abort the txn - just to close a cursor.

And without MDB_VL32, plain cursor closing after txn abort seems to work just fine (I did not consider "closing" as "using" when I read the docs). One could say that the inconsistent behavior is a result of the complexity MDB_VL32 introduces.

If you don't want to change the current behavior, it would still be nice for future developers to null the obsolete txn ptr in the cursor on txn abort to make the unwanted close call crash always, not just occasionally.