We're currently using SSRS 2016 (the unpatched RTM) in Native mode and we've run into an issue that occurs rarely, but often enough to be a problem. When viewing a report, leaving it up on the screen for a while (more than a few minutes, but it doesn't always occur) and then coming back later and trying to expand a group or open a separate segment of the report results in an exception:
Sys.Webforms.PageRequestManagerServerErrorException: An unknown error occurred while processing the request on the server. The status code returned from the server was: 500
Unfortunately that's pretty generic and not much help - I found an ASP.NET 4.0.30319.0 "Warning" (Event ID 1309) in the server's application event log that has a bit more detail (snipped a bit to show what seems like the relevant portions):
Event code: 3005
Event message: An unhandled exception has occurred.
Event detail code: 0
Application domain: ReportServer_MSSQLSERVER_0-34-131190290606090156
Trust level: RosettaSrv
Application Virtual Path: /ReportServer
Application Path: C:\Program Files\Microsoft SQL Server\MSRS13.MSSQLSERVER\Reporting Services\ReportServer\
Process ID: 1600
Process name: ReportingServicesService.exe
Exception type: ArgumentNullException
Exception message: Value cannot be null.
Parameter name: exception
at System.Web.UI.AsyncPostBackErrorEventArgs..ctor(Exception exception)
at System.Web.UI.PageRequestManager.OnPageError(Object sender, EventArgs e)
Has anybody seen this before? It's occurring on all three of our servers (we have a scale-out deployment), but it only happens once every few days or so (about once/week per server). I don't think it's not a strict timeout, as I've let a report sit open on the site for hours and then browsed around with no issue at all.
There's a CU out for SQL 2016 that we're going to apply in our lab to see if that resolves it, but I wanted to see if anybody here had thoughts before we do that.