After upgrading the SQL Server Reporting Service to 2016, the SSRS reports embedded in different applications including SharePoint pages using an iframe tag or page viewer web parts were stopped rendering.
I tried to fix this issue by adding the following entries in the rsreportserver.config but no luck.
The rsreportserver.config file is installed in the following location by default:
C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\WebServices\Reporting
C:\Program Files\Microsoft SQL Server\MSRS13.MSSQLSERVER\Reporting Services\ReportServer
Added rs:Embed=true as a query parameter at the end of the report URL and this fixed the issue and reports started working properly.