This hotfix applies to Microsoft SQL Server 2012 Reporting Services (SSRS 2012) and SQL Server 2014 Reporting Services (SSRS 2014).
When you try to pass some parameters that cause the URL length to exceed 65,520 characters for a Microsoft SQL Server 2012 Reporting Services (SSRS 2012) or SQL Server 2014 Reporting Services (SSRS 2014) report, you cannot render the report, and you may receive the following error message:
The value of parameter 'param' is not valid. (rsInvalidParameter).Invalid URI: The Uri string is too long.
When you render the report in a format other than HTML, the rendering process may be successful. However, the generated file is corrupted and contains the previously mentioned error.
After you install this hotfix, the rendering operation will complete successfully on all rendering extensions without producing corrupted files for situations in which the URL (with parameters) has a length that exceeds 65,520 characters. However, ExecutionLog will trace a warning if the URL length exceeds 65,520 characters.
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:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.