XDCR replication error from 5.1.1 to 2.2.0 (community edition) using XMEM (v2)



I am trying to create a bi-directional replication between Couchbase server 2.2.0 and 5.1.1 (both community editions) using XDCR v2 (XMEM) for performing upgrade. From http://docs.couchbase.com/couchbase-manual-2.2/#cross-datacenter-replication-xdcr, I can confirm that XMEM is available from 2.2 onwards.

I am able to successfully create a XDCR replication from 2.2.0 to 5.1.1 using XDCR v2 and verify that it works. However, when establishing a replication from 5.1.1 to 2.2.0 using XDCR v2, I get the following error:

“2018-11-05 14:19:03 xxx.xxx.xxx.xxx:Invalid configuration. Xmem replication type is specified when the target cluster, xxx.xxx.xxx.xxx:8091, is not xmem compatible.”

I am able to establish a XDCR replication through XDCR v1 (CAPI) though. I do not understand why XMEM works from 2.2.0 to 5.1.1 but not the other way around.

Has anyone else faced the same issue? Any help would be appreciated. Thanks.