By testing MongoDB connection it threw the following error.
=====
The full response is
{ 
  "ok" : 0.0, 
  "errmsg" : "not authorized on Database Name to execute command { dbstats: 1 }", 
  "code" : 13, 
  "codeName" : "Unauthorized" 
}
=====
This error occurred due to the user not being granted the role "read" or "readWrite" .
 

By testing the MongoDB shared connection resource it threw the error "not authorized on database name to execute command "

ALL Os

To resolve this error follow the steps below.

1). Start the mongod instance using the command: 
  $ mongod --auth

2). Start the mongo shell and create an administrator in the admin database:
$ mongo
> use admin
> db.createUser(
  {
    user: "User",
    pwd: "PW",
    roles: [ { role: "userAdminAnyDatabase", db: "DB name" } ]
  }
)

3). Executing the command db.stats()and will get an error "not authorized on DB name to execute command" 
> db.stats()
{
        "ok" : 0,
        "errmsg" : "not authorized on admin to execute command { dbstats: 1.0, scale: undefined }",
        "code" : 13,
        "codeName" : "Unauthorized"
}

4). To resolve this error execute the following command.
> db.auth("User", "PW")
> db.grantRolesToUser("User", [ { role: "read", db: "DB name" } ])

5).To verify the role given to the user, execute the command > db.stats() will get a successful result.

6). Configure the MongoDB connection and test connection.Then connection will be successful.

https://stackoverflow.com/questions/35881662/show-dbs-gives-not-authorized-to-execute-command-error