error: Unit mongodb.service is masked when starting mongodb

Question

I'm trying to install kaa(IOT platform) on installing the dependencies getting an error on executing the command-

$ sudo systemctl start mongodb
error- Failed to start mongodb.service: Unit mongodb.service is masked.

Answer 1

Unit mongodb.service is masked.

So unmask it:

sudo systemctl unmask mongodb

Why are some systemd services in the "masked" state? explains masking.

Answer 2

With 3+ version of mongodb. You dont have to start mongodb but you just have to start mongod. So proper way to start mongod will be

sudo systemctl start mongod