Microsoft Report Viewer |top|

This example creates a new Report Viewer control, sets the report source to a report file (.rdlc), and adds the control to a Windows Forms application.

Once the layout is ready, you use C# or VB.NET to fill it with actual content. Local Processing microsoft report viewer

// Set the report source reportViewer.LocalReport.ReportEmbeddedResource = "Report1.rdlc"; This example creates a new Report Viewer control,

The report server handles all data retrieval and processing. | Problem | Likely Cause | Solution |

| Problem | Likely Cause | Solution | |---------|--------------|----------| | "A data source instance has not been supplied" | Forgot to add ReportDataSource | Verify DataSources.Clear() and Add() before RefreshReport() . | | Report Viewer is blank/empty | Incorrect report path | Use absolute or Application.StartupPath + @"\Reports\file.rdlc" . | | PDF export cuts off columns | Page width mismatch | In RDLC designer, set Report Properties → Page Size → Width to 11in (Landscape). | | Could not load file or assembly 'Microsoft.ReportViewer.Common' | Missing NuGet or broken reference | Reinstall the package. Check bin folder for the DLL. | | WinForms control freezes on large data | Synchronous rendering | Use reportViewer.SetDisplayMode(DisplayMode.PrintLayout) and call RefreshReportAsync() . | | Parameter dropdowns don't filter correctly | Missing @ParameterName in dataset query | Ensure query uses WHERE Column = @ParameterName . | | Subreport not showing data | Subreport processing event not wired | Hook event before calling RefreshReport . | | Printing from WinForms fails | Print dialog hidden behind modal | Use reportViewer.PrintDialog() on a separate thread with BeginInvoke . | | ASP.NET: Unable to load embedded resource | Missing WebForm ScriptManager | Add <asp:ScriptManager ID="sm1" runat="server" /> . | | .NET 6: TypeLoadException | Mixed Framework targeting | Use Microsoft.Reporting.WinForms (not legacy package). |