I have multiple reports created in Report Designer with the same error condition. Each has one or more report parameters that have an entity datasource (sql server stored procedure) and set to multivalue=true and set to null=yes and have no initial value set. These are passed as arguments to the stored procedure for the main datasource. Having no selections is a valid condition.
When run through our web application, when the report initially displays each of those multi-select parameters it displays the "Please input a valid value" error message. Usually when this happens, the report engine pauses, additionally displays the "Please input valid data for all parameters" message as well, then waits for more user input.
However this is not happening: the "Please input..." message is not being displayed, and the report jumps right in and does an initial rendering to the web page. This indicates it thinks it does not have any invalid parameters. Yet, the Preview button is not clickable indicating it thinks there are invalid parameters. Very confusing.
The work-arounds include:
1) Select one item in the parameter list, then un-select it. Now the Preview button works.
2) In report designer, force an initial selection of one item in the report parameter.
3) In report designer, change the report parameter to be single value instead of multi value.
4) In report designer, run the report in preview mode - it runs fine with no error messages.
None of these are good solutions of course. So I need to know how to suppress the seemingly erroneous parameter errors.
Telerik 188.8.131.52 Windows 10 VS 2015 SQL Server 2016. This happens when running locally through VS as well as when deployed to a separate server.