Upgrading SharePoint 2010 projects to 2013

• Open your csproj in notepad.
• Change the Target Framework Version from v3.5 to v4.5 <TargetFrameworkVersion>v4.5</TargetFrameworkVersion>
• Set the Office Target Version to 15 by entering the following tag to the file below TargetFrameworkVersion tag. <TargetOfficeVersion>15.0</TargetOfficeVersion>
• Update all referenced assemblies;
  • SharePoint assemblies from version 14.0.0.0 to 15.0.0.0
  • .NET assemblies from 2.0 and 3.5 to 4.0 and 4.5
•  Go to each file (eyeball and replace them one at a time):
• Replace all 14.0.0.0 in user controls and web parts to 15.0.0.0
• Replace all version 12.0.0.0 in Pagelayouts to 15.0.0.0. Look specifically at:
  <%@Register TagPrefix=”SharePoint” Assembly=”Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c” namespace=”Microsoft.SharePoint.WebControls”%>
• Build the project to check for any compilation errors and re-adjust.
• Update list definitions  to take advantage of the new view styles.
• For all user control and delegate references:Change from:  ~/_controltemplates/..To: ~/_controltemplates/15/
• Change all reference of /_layouts/ to /_layouts/15/
• Go to the Package.Template.xml and add SharePointProductVersion=”15.0″
  <?xml version=”1.0″ encoding=”utf-8″?>
  <Solution xmlns=”http://schemas.microsoft.com/sharepoint/&#8221; SharePointProductVersion=”15.0″>
  </Solution>
• Make sure that the elements in package.package SharePoint Product Version is set to 15.0