A replica set secondary crashed with the following assertion error:

2017-05-11T09:05:17.741-0400 F REPL     [repl writer worker 3] writer worker caught exception:  :: caused by :: 11000 E11000 duplicate key error <redacted>
2017-05-11T09:05:17.745-0400 I -        [repl writer worker 3] Fatal Assertion 16360
2017-05-11T09:05:17.745-0400 I -        [repl writer worker 3]

***aborting after fassert() failure

At the time the primary was under load, servicing 3.6k reads and 132 writes per second. The other replica set secondary was being rebuilt at the time this one crashed.

There are multple 'duplicate key' errors in the primary's log, where documents were rejected on insert, but none are the document reported as duplicate by the secondary that crashed.

MongoDB 3.2.11 on Amazon Linux, version 2106.03
mongo setup: three node replica set, one primary, two secondaries