Change the name of an internal HDD
I eventually found my own answer.

The error is caused because the the account is looking in the wrong place for the home directory. 
If you change the name of the internal drive which contains your accounts Home Directory you must also update the pointer to the Home Directory.
You can do this by going to 


System Preferences -> Users &amp; Groups
Right-click your Username and select Advanced Options
Change the value next to Home Directory to match your new location.


In my case I changed:

/Volumes/High Sierra HDD/&lt;Username&gt; to /Volumes/HighSierraHDD/&lt;Username&gt;

Apple provides instructions of how to do this, as well as other changes you can make to your account, here.

Be warned because I have my OS installed on one drive and my home drive on the other you may get different results when you change yours.