Symptoms
Assume that you use Microsoft SQL Server 2016 Reporting Services (SSRS 2016) in SharePoint integrated mode. When you open a report in local mode, you may receive an error message that resembles the following:
Unable to cast object of type 'Microsoft.Reporting.WebForms.LocalReport' to type 'Microsoft.Reporting.WebForms.ServerReport'.
Resolution
This issue is fixed in the following cumulative update for SQL Server:
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:
More Information
For more information about the local mode and connected mode reports, you can go to the following Microsoft website:
Local Mode vs. Connected Mode Reports in the Report Viewer
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
Learn about the terminologythat Microsoft uses to describe software updates.