The breakpoint will not currently be hit in Silverlight project

Solution 1:
1. Right click on the Silverlight project
2. Locate and click the Web tab
3. Make sure that the Silverlight checkbox is checked.

Solution 2: What if the Silverlight checkbox is already checked, you have already cleaned the solution, deleted the BIN and OBJ folders and still, it doesn't work?
1. Uncheck the Silverlight checkbox
2. Run the solution (the breakpoint will not work, of course!)
3. Stop running. Go the properties again and re-check the Silverlight option.
It works for me!

Solution 3: Clear the browser's cache / temporary files

Solution 4: Usually deleting the <solutionfilename>.suo file in the solution folder fixes it.

Telerik Report: RendererNotAvailableException... rendering format is not available

Scenario: I am trying to export the report programmatically
Feature: Telerik Reporting export feature
Error Message: "RendererNotAvailableException... rendering format is not available" for the following formats:

- DOCX
- HTML
- PPTX 
- XPS

Code Snippet: 
Telerik.Reporting.Processing.ReportProcessor reportProcessor = new Telerik.Reporting.Processing.ReportProcessor();
Telerik.Reporting.Processing.RenderingResult result = reportProcessor.RenderReport(format, reportToExport, deviceInfo);
 reportBytes = result.DocumentBytes;
 if (reportBytes != null && reportBytes.Length > 0)
                Mailer.SendNotifications(_report, reportBytes);

Solution:

As noted in the Deploying Applications using Telerik Reporting help section, the DOCX/PPTX/XLSX rendering extensions require Telerik.Reporting.OpenXmlRendering.dll and Open XML SDK 2.0 for Microsoft Office (DocumentFormat.OpenXml.dll v.2.0.5022.0 or above).

The XPS rendering extension requires Telerik.Reporting.XpsRendering assembly (Telerik.Reporting.XpsRendering.dll). In both cases your project should be targeting .NET 3.5 Framework or above.

If just adding the DocumentFormat.OpenXml.dll does not work, then, the

Open XML SDK 2.0 for Microsoft Office must be installed first on the server.

If still, it doesn't work, check the project that references to the project where Telerik Reporting is originally referenced. That project also needs the mentioned DLLs.

The 'Microsoft.ACE.OLEDB.12.0' provider is not registered on the local machine.

Problem Summary:
I am getting the above error when I'm trying to import data from excel file in the production server. But, import excel is working on my local machine.

Cause:
The server does not have the proper DLL installed.

Solution:
Install the Office System Driver: Data Connectivity Components in the server.

DOCX rendering format is not available.

This error happens when a Telerik report is to be exported to Word document programmatically.

Take a look if the following DLLs are referenced:
Telerik.Reporting.OpenXmlRendering.dll
DocumentFormat.OpenXml.dll
Telerik.Reporting.XpsRendering.dll (for Xps file)

Note:
If just adding the DocumentFormat.OpenXml.dll does not work, then, the
Open XML SDK 2.0 for Microsoft Office must be installed first on the server.

Reference:
http://www.telerik.com/community/forums/reporting/telerik-reporting/report-export-to-docx.aspx