start session, open transaction in this session write documents with several duplicated keys expected: write errors about all duplicates actual: 1 write error @Test public void transactionalCase() { ClientSession session = dbFactory.getSession(ClientSessionOptions.builder().build()); Document document1 = Document.parse( "{_id:1, value: 1}" ); Document document2 = Document.parse( "{_id:2, value: 2}" ); Document document3 = Document.parse( "{_id:1, value: 3}" ); Document document4 = Document.parse( "{_id:1, value: 4}" ); session.startTransaction(); try { collection.insertMany(session, List.of(document1, document2, document3, document4), new InsertManyOptions().ordered( false )); Assert.fail( "insertMany should fail" ); // session.commitTransaction(); } catch (MongoBulkWriteException e) { session.abortTransaction(); Assert.assertEquals(e.getWriteErrors().size(), 2, "Expected to have 2 dup key errors:" ); // fails here! } finally { session.close(); } }