Bug introduced in 10.0.0. Fixed in 10.4.0

I think I found a bug in KeyIntersection (Mma 10.2). To illustrate, input the following:

KeyIntersection[{Association[], Association[]}]

This returns KeyIntersection[{<||>, <||>}] instead of {<||>, <||>}. Only one of the inputted associations need be empty to create this problem.

Am I right that this is a bug? If so, is it fixed in 10.3?

  • 1
    $\begingroup$ The output is the same in 10.3 $\endgroup$
    – Kuba
    Nov 13, 2015 at 22:08
  • $\begingroup$ I interpret the up votes as agreement that this is a bug. Therefore I have reported it as such. $\endgroup$
    – Alan
    Nov 15, 2015 at 22:38
  • $\begingroup$ Keep us informed about the response $\endgroup$
    – Kuba
    Nov 15, 2015 at 22:50

1 Answer 1


This was still broken in version 10.3.1, but is fixed from version 10.4.0 onward (at least up to version 11).

(* "10.4.0 for Microsoft Windows (64-bit) (February 26, 2016)" *)

KeyIntersection[{Association[], Association[]}]
(* {<||>, <||>} *)

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