Re: Intermittent error: Missing Parameter Values, while exporting to PDF

Hello Ludek,

This has been a difficult problem.

The report initially was based on a .NET DataTable object that was fully populated before loading the report and before setting it as the DataSource of the report.

The root problem has not being solved yet, although it has changed its form.

Below are the stages that the problem has had:

1. The error that was reported in the first message: "Missing parameters values".
2. I redesigned the report to have no parameters.  This worked for about one day and then again appeared an error: "Database logon failed".  We had the report unavailable for 2 days because we didn't want to restart the IIS, but to try to solve the problem with the report when the failure was present.
3. Before restarting the IIS (which I assume would have solved problem #2 as it solved #1) I changed again the reports.  They are now based on a XML file that is generated completely before assigning it as the DataSource of the report.  This worked for about two weeks, and then another error appeared: the reports come up in blank.  When the IIS is restarted all reports begin to work.

I think the main things to notice here are:

1. The problem is intermittent, one report with certain parameters (no real report parameters, just parameters indicated in the screen by the user) works fine and then suddenly fails.
2. The problem is solved by restarting the IIS, without doing anything else.
3. The problem is not reproduced in the test environment.  We have tested the reports in the test environment using a copy of the production database.  We had 5 users requesting very large reports simultaneously, and no error was found.

These things indicates that this could be a bug of some kind, related to Crystal Reports and also related to the work load of the server, because the problem is not reproduced in the test environment, using similar conditions.

I have tried to overcome the problem by changing the design of the reports, but it seems that suddenly there is a failure and once it occurs it can't be solved by a way other than restarting the IIS.

Maybe there is a way of generating the reports that would avoid this problem, but I have come to think that to solve this it would be necessary to use another reporting tool, not Crystal Reports.