Libcouchbase crash when I restart couchbase-server during inserts

I installed and configured 2 couchbase(community edition) nodes in a cluster.
I Connected to the cluster with the client and started inserting elements.
I Couchbase client is running in the same machine where 1st couchbase-server node running.
When i restart the 1st couchbase-server node(where client is running). I hit an assert statement and client crashes.
FYI: It doesnt crash when i restart the 2nd couchbase-server node
Version: 2.1.1 community edition (build-764)

In the client app code, each thread is using a seperate instance to connect to the cluster
What am i doing wrong?

Below are the logs and back trace

Config connection considered stale. Reconnection forced
SampleReplClientApp: src/bconf_io.c:150: instance_timeout_handler: Assertion `instance->confstatus != LCB_CONFSTATE_CONFIGURED’ failed.

#0 0x00000035e5a32885 in raise () from /lib64/
Missing separate debuginfos, use: debuginfo-install dre-3.4.0-02.x86_64 glibc-2.12-1.47.el6.x86_64 libevent-1.4.13-1.el6.x86_64 libgcc-4.4.6-3.el6.x86_64 libstdc+±4.4.6-3.el6.x86_64 zlib-1.2.3-27.el6.x86_64
(gdb) bt
#0 0x00000035e5a32885 in raise () from /lib64/
#1 0x00000035e5a34065 in abort () from /lib64/
#2 0x00000035e5a2b9fe in __assert_fail_base () from /lib64/
#3 0x00000035e5a2bac0 in __assert_fail () from /lib64/
#4 0x00000034be804d60 in instance_timeout_handler (conn=, err=) at src/bconf_io.c:150
#5 0x00007fdc96400b44 in event_base_loop () from /usr/lib64/
#6 0x00000034be813c42 in lcb_wait (instance=0xbff52f50) at src/wait.c:77
#7 0x000000000041453a in CouchbaseConnector::CreateEntry (this=0xbff20b80, key=“”, entry=0x7fdc94be2c94, entryLen=28) at src/CouchbaseConnector.cpp:234
#8 0x000000000040aab6 in ReplicationThread::Run (this=0xbff66a40, arg=0x0) at src/ReplicationConnectorThreadPool.cpp:128


What version of libcouchbase?