SharePoint 2013 Issue – Custom Web Part results in Could not load file or assembly after upgrade
After an upgrade of a SharePoint 2010 content database to SharePoint 2013 you may get an error message “Could not load file or assembly ‘MyCustomWebPart, Version=1.0.0.0, Culture=neutral, Public Token=6912jju2191j213ggv10’ or one of its dependants. The system cannot find the file specified” when you try to access a page.