System.Web.Services.Protocols.SoapException: The permissions granted to user 'IIS APPPOOL\MyUser' are insufficient for performing this operation

I had this error (System.Web.Services.Protocols.SoapException: The permissions granted to user 'IIS APPPOOL\MyUser' are insufficient for performing this operation) and took me a while to work out what to do to fix it. All the references I found  to it were relating to SharePoint.

In my instance I had added a web reference to my application to make use the reporting services (SSRS) web service (http://localhost/ReportServer/ReportExecution2005.asmx). Although it was working locally, it was not working when I deployed it to the dev or live server.

Turns out the account that is used by the reporting services service account needed to be the same as the account that the application pool was using.

So check the service account in the reporting services configuration tool:

Then from within the IIS, change the identity that the application pool is using (right click the pool and choose Advanced Settings...):

FYI, here's the full error message:
System.Web.Services.Protocols.SoapException: The permissions granted to user 'IIS APPPOOL\MyUser' are insufficient for performing this operation. ---> Microsoft.ReportingServices.Diagnostics.Utilities.AccessDeniedException: The permissions granted to user 'IIS APPPOOL\MyUser' are insufficient for performing this operation. at Microsoft.ReportingServices.WebServer.ReportExecution2005Impl.LoadReport(String Report, String HistoryID, ExecutionInfo2& executionInfo) at Microsoft.ReportingServices.WebServer.ReportExecutionService.LoadReport(String Report, String HistoryID, ExecutionInfo& executionInfo)