Rocketchat: New user registration is currently disabled

You may enable New User Registration by running a couple of commands in your rocketchat mongo shell

Open your mongo shell by something like this

mongo -host localhost -port 27017

This will show your mongo shell version as a success a message
MongoDB shell version: 3.2.12

Then run this command

use rocketchat 

Then:

db.rocketchat_settings.find({"_id": "Accounts_ShowFormLogin"});

(this should show a value set to false in your case)

Now run

db.rocketchat_settings.update({_id:'Accounts_ShowFormLogin'}, {$set: {'value' : true} });

WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

We’re DONE.
Restart your rocketchat.