In this article I will explain with an example, how to resolve the error: Could not load file or assembly 'Microsoft.ReportViewer.WebForms, Version=10.0.0.0.
 
 

Cause

The following error occurs, when you use incorrect or incompatible versions of the Microsoft.ReportViewer.WebForms assembly or its dependencies.
Server Error in '/' Application.
 
Configuration Error
 
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.
 
Parser Error Message: Could not load file or assembly 'Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.
 
 

Solution

In order to get rid of this error, you need to make sure that the ReportViewer version you are using is correct and compatible with the referenced project .Net Framework.
If it is not compatible, then update the version according to the requirement.