the report execution has expired or cannot be found. (rsexecutionnotfound)

I was working on some reports and the report was rendered successfully. Then i went to have my lunch and then came back and to fetch the latest data, I clicked on referesh and Bammmm!!, I was hit with a error "the report execution has expired or cannot be found. (rsexecutionnotfound)"

Specific Error: the report execution wouibt55ln003rijpxkrbu45 has expired or cannot be found. (rsexecutionnotfound)

I was quite worried so as to what happened. Then I went back and then again re-run the report and it was successful. I was quite amazed so as to what happened. Then I went in the logs and check for errors, then I could see the below error.

ERROR: Throwing Microsoft.ReportingServices.Diagnostics.Utilities.ReportServerStorageException: , An error occurred within the report server database.  This may be due to a connection failure, timeout or low disk condition within the database.;

ERROR: Error in getting session data: Invalid or Expired Session: wouibt55ln003rijpxkrbu45

ERROR: Throwing Microsoft.ReportingServices.Diagnostics.Utilities.ExecutionNotFoundException: , Microsoft.ReportingServices.Diagnostics.Utilities.ExecutionNotFoundException: The report execution wouibt55ln003rijpxkrbu45 has expired or cannot be found.;

Here "wouibt55ln003rijpxkrbu45" is my session name on which the report is run. What has happened here is when a Session is opened to Run a Report, it has certain rules to follow. Yes, a Timeout is set to this Session on which the Report is run, which is default 600 seconds and after the timeout period, the Session expires. This was the reason I got the above error.

Well, there is a interesting fact, this Timeout period is not only for Idle sessions but also for running reports as well. If a report is in exeuting state for more time then the Timeout value then, you will end up in same error.

To resolve the second case, You can increase the Report Time out Value in site settings or Increase the Timeout value in Report Execution Properties and then Re-Deploy report.