Describe the issue

I installed bitcoin-cli but i can't run it.
I got an error : "make sure server is running and you are connecting to the correct RPC port"

What version of bitcoin-core are you using?

0.14

Machine specs:

• OS: Ubuntu Server 14
• CPU: Intel® Xeon® E3-1270
• RAM: 16 GB
• Disk size: 600 GB
• Disk Type (HD/SDD): SSD