I am trying to install Mongo DB on a windows 8.1 64 bit machine and I a getting the following error.
C:\MongoDB\bin>mongo.exe
MongoDB shell version: 2.4.7 connecting to: test Tue Nov 19 14:50:02.652 Error: couldn't connect to server 127.0.0.1:27017 at src /mongo/shell/mongo.js:145 exception: connect failed
Use this link. I also faced lot of problems when installing.But before found this link.
Make sure you have the daemon process running. You start it via mongod.exe. You are running the client side and by default connecting to port 27017 - the default mongo instance. Check your running processes for mongod first!
Make sure to unclick the download compass section when you download the shell. As soon as I unclicked it I was able to install the Mongodb shell. Hope this helps - I was stuck with this problem for a long time.
来源：https://stackoverflow.com/questions/20061809/issue-with-installation-of-mongo-db-on-windows-8-1