Generally this should work as per the documentation, but it ain't working if you are trying to execute from the server after connecting to "mongo.exe"

mongoimport --db test --collection restaurants --drop --file ~/downloads/primer-dataset.json

Instead, before even entering the mongo.exe console, at bin, the below command is importing the data -

mongoimport.exe --db test --collection restaurants --drop --file ~/downloads/primer-dataset.json