I’ve seen a few people get confused over what this error message in the Reporting Services log file indicates. This message is generated when the Reporting Services web server detects that an HTTP request has experienced a remote disconnect. In practice, this means that we queried the property HttpResponse.IsClientConnected and it returned false.
So how does this work exactly, and are all requests subject to this kind of check? As Reporting Services is currently architected, not all operations are subject to this check. For potentially long-running operations (such as report renderings and interactivity operations – internally we refer to these as Cancelable operations) requests are registered with a central request manager, which has a thread which wakes up periodically to check whether or not the clients are still connected. If they are not, then we begin the process of aborting that request on the server side in order to reclaim any resources that it is consuming.
Basically every operation on the ReportExecution2005.asmx endpoint, as well as the UpdateReportExecutionSnapshot(), CreateReportHistorySnapshot(), GetReportParameters(), and GetUserModel() methods on the ReportService2005.asmx endpoint register themselves as potentially long running operations.
So what should you do if you are seeing a lot of these errors in the log? Generally this is an indicator that requests are being torn down for some reason. This could be due to certain set of users being particularly impatient waiting for report results to return and closing their browser. Alternatively, we have seen some cases in the wild where certain proxies would internally time out requests after waiting for some period of time, at which time they close the connection to the Report Server. If you have such a deployment topology (proxy/load balancer between clients the Report Server) definately consider checking if such a configuration knob exists for your environment.