hello cannot locate the core snap: No such file or directory

Solution 1:

I have the hello snap, notes and core installed on my computer and all of them work fine.

$ snap list
Name              Version           Rev  Developer         Notes
core              16.04.1           714  canonical         -
hello             2.10              20   canonical         -
notes             0.9.0~gitb6e3b34  4    notes-developers  -  

When the hello snap is installed, the core snap is installed along with it if core is not already installed. Try updating the core snap:

sudo snap refresh core  

If core is already installed the following message will be shown:

snap "core" has no updates available

Your results of running sudo snap refresh core were as follows:

sudo snap refresh core error: cannot refresh "core": cannot find snap "core"

So uninstall the core snap and then reinstall it.

sudo snap remove core hello  
sudo snap install hello # core will also be installed automatically

Hello is a terminal app that runs like this.

$ hello
Hello, world!

Solution 2:

I did:

sudo snap install core

And that did the trick. Thanks for pointing me in the right direction!