We recently upgraded from SQL Server 2008 R2 to SQL Server 2012 SP 2. Our reports accept a "psetofscopes" parameter which is a comma-delimited string which we in turn pass to a STRTTOSET function in MDX queries. The format of the string is
"[DDDD].[HHHH].&[1234],[DDDD].[HHHH].&[4321], ... "
Where DDDD represents the dimension and HHHH represents the hierarchy.
The problem occurs when the length of the parameter exceeds 64K (65536 characters). Calling the report works fine. However, when the report calls another report, via the "Go to Report" action, the call to the "sub-report" aborts with
Microsoft.ReportingServices.Diagnostics.Utilities.InvalidParameterException: The value of parameter 'pSetOfScopes' is not valid. ---> System.UriFormatException: Invalid URI: The Uri string is too long.