Following an upgrade from SharePoint 2010 to 2013 I deployed some custom web parts.  When loading the page I received the error “/_CONTROLTEMPLATES/WEBPARTNAME/VisualWebPart1/VisualWebPart1UserControl.ascx” does not exist.

The error is caused by the web part looking in the \14\TEMPLATE\CONTROLTEMPLATES folder rather than \15\TEMPLATE\CONTROLTEMPLATES.  Open the web part solution in Visual Studio and change the _ascxPath string.  Original value below:

Change the string to include the 15 folder.

Rebuild and re-deploy the web part.