If you build a web application with Chart control for ASP.NET 4.0 and deploy the site to web server.  You might get following error on the live site:

The temp directory in chart handler configuration is not accessible

To resolve this, first go to web.config and find the ChartImage directory in appsettings.

<add key="ChartImageHandler" value="storage=file;timeout=20;dir=c:TempImageFiles;" />

The go to the temp chart image directory and grant read and write permission to IIS working process account in share properties – security tab. Note that the account runs IIS working process is different between IIS 7 and IIS 7.5

  • On Windows Server 2008 has IIS7, grant Read and Write permission to Network Service
  • On Windows server 2008 R2 has IIS 7.5, grant Read and Write permission to AppPool<PoolName>. Replace <PoolName> to the actual machine pool your site is running on, for example, if your site is running on pool named ASP.NET v4.0, then the account you need grant permission would be IIS AppPoolASP.NET v4.0, you can refer this step by step instructions for detail