mongod rs.initiate() error msg

Question

I am a newbie so please bear with me.
I have used this command $ sudo mongod --config /etc/mongod2.confin terminal to start a mongodb service instance. In another terminal I ran $ mongo --port XXXX where XXXX is the port number I configure in mongod.conf file. rs.initiate() in mongo shell is giving the error "errmsg" : "assertion src/mongo/db/repl/replset_commands.cpp:275", "code" : 8 why ?

edit: **mongodb version v3.2.12**
mongod2.conf file consist of:

# for documentation of all options, see:
# http://docs.mongodb.org/manual/reference/configuration-options/
# Where and how to store data.
storage: dbPath: /var/lib/mongodb2 journal: enabled: true
# engine:
# mmapv1:
# wiredTiger:
# where to write logging data.
systemLog: destination: file logAppend: true path: /var/log/mongodb2/mongod.log # network interfaces
net: port: 27019 bindIp: 127.0.0.1
processManagement: fork: true #security:
#operationProfiling:
replication: replSetName: myDevReplSet

Answer 1

I created multiple copy of mongod.conf naming mongod1.conf , mongod2.conf and so on in which I specified dbpath as /var/lib/mongodb1, /var/lib/mongodb2 and so on (as you can see in the edit section of mongod2.conf) and it works fine.If there doesn't exist folder /var/lib/mongodb1 then it automatically creates it or you should just create the folder. Now you can use replica set.