SharePoint 2013 $Resources:core,ImportErrorMessage;

This happened to me whilst I was trying to debug my WebPart from Visual Studio, always after the ‘first’ debug session it failed to re-load and thus, threw the below when launching the 2nd debug session.

$Resources:core,ImportErrorMessage;

I found what worked for me was:

Visual Studio -> Build -> Select ‘Retract’

Upon doing so, I was able to Clean the solution, re-deploy and then finally start debugging as normal. I know it’s quite a small thing, but other resources on the web was also suggesting to:

  • Add Guid Attribute to the WebPart (To make sure there’s no mis-match)
  • Rename the WebPart to .wsp
  • Restart Visual Studio and the debugging browser all together (With Admin rights too!)