Json encoder/decoder throws Server error during processing:{what,{ucs,{bad_utf8_character_code}}},mochijson2,json_encode_array,2},

Setup:
----------
1. Setup a 10:10 node xdcr replication on 2 buckets, with bidirectional xdcr and unidirectional xdcr on the buckets.
2. XCDR is working as expected.

Unable to read any information from server, getting error
Server error during processing: ["web request failed",
{path,"/pools/default/tasks"},
{type,exit},
{what,{ucs,{bad_utf8_character_code}}},
{trace,
[{xmerl_ucs,from_utf8,1},
{mochijson2,json_encode_string,2},
{mochijson2,'-json_encode_array/2-fun-0-',
3},
{lists,foldl,3},
{mochijson2,json_encode_array,2},
{mochijson2,
'-json_encode_proplist/2-fun-0-',3},
{lists,foldl,3},
{mochijson2,json_encode_proplist,2}]}] (repeated 11 times)

Unable to get any task definitions
http://ec2-175-41-184-132.ap-southeast-1.compute.amazonaws.com:8091/pools/default/tasks
http://ec2-122-248-222-144.ap-southeast-1.compute.amazonaws.com:8091/pools/default/tasks

Seeing this after running the cluster for 1-2 days, not seen similar errors on the begining of the test.

[Dont have cluster ssh access currently and will upload logs shortly.]
The clusters are accessible at
http://ec2-175-41-184-132.ap-southeast-1.compute.amazonaws.com:8091/
http://ec2-177-71-147-19.sa-east-1.compute.amazonaws.com:8091/

@Abhinav - Can we add the complete diags on this one?