You might have come to this page as you encountered same error as mine. I am using Glassmapper as ORM for Sitecore.
There are many reasons for this error. Below are couple of them.
- Make sure you are passing in right datsource template for your rendering. If your rendering is not expecting any datasource make sure u have datasource field empty on presentation.
- If you are in multi-lingual environment, make sure all the items needed by the rendering have this language version, Using language fallback helps in this