I have often irritated me lately with the following error:
The selected report is not ready for viewing. The report is still-being rendered or a report snapshot is not available. (RsReportNotReady).


This error originated in a given reporting when you change a parameter on top of the report. The strange thing was that the error may or may not be generated! Got a lot of different solutions tried were found on the Internet, but nothing helped.

Then I have the report in Report Designer opens with the same parameter as in Report Manager. The error arose that deviated from the error in Report Manager:


Then I used some expressions in the matrix-groups were amended and the error was gone! The error Sat therefore a group expression.

My conclusion is that the error message had nothing to do with the cause of the error. Microsoft Reporting Services generates this error randomly. Will see this warning, check the contents of your report in lieu of all other matters on the Internet are called!