Report name in report contract cannot be null or empty.

 I ran into this issue while running the invoice journal report.

After spending sometime, I'm able to find the solution. To fix this issue just run  the following code in the runnable class:

class RunnableClass
{
    /// <summary>
    /// Run the class with the specified arguments.
    /// </summary>
    /// <param name = "_args">The specified arguments.</param>
    public static void main(Args _args)
    {
        PrintMgmtReportFormat                     printMgmtReportFormat;
        

        ttsbegin;
        select forupdate printMgmtReportFormat
            where printMgmtReportFormat.Name == 'ReportName.Report';
        printMgmtReportFormat.System = NoYes::Yes;
        printMgmtReportFormat.doUpdate();
        ttscommit;
    }
}