Error with Telerik Reporting and OpenAccessDataSource

[almostEric]

After using Telerik reporting for over 10 years, with the latest update we are now getting this error when trying to print a report.

Looks like we now need to add something to our app.config file.

Would be cool if this were documented somewhere

[Ivet]

Hi Eric,

Thank you for the provided screenshot of the error.

The type Telerik.Reporting.OpenAccessDataSource is part of the Telerik.Reporting.dll assembly and is used to connect Telerik Reports to a Telerik Data Access Model.

You are encountering a new configuration requirement introduced in recent Telerik Reporting versions. Starting with the 2024 Q3 release (18.2.24.924), type restrictions were tightened for security reasons. Custom assemblies, such as those used in ObjectDataSource or OpenAccessDataSource, now need to be explicitly listed in your application's configuration file.

This change is a security measure to prevent unauthorized usage of assemblies within reports. Previously, your app.config did not need these customizations, but the updated version enforces stricter type checks.

Add an <AssemblyReferences> section under the <Telerik.Reporting> configuration in your app.config or web.config. List each required assembly by name. Here’s an example:

<configuration>
  <configSections>
    <section name="Telerik.Reporting"
             type="Telerik.Reporting.Configuration.ReportingConfigurationSection, Telerik.Reporting, Version=19.2.25.1001, Culture=neutral, PublicKeyToken=a9d7983dfcc261be"
             allowLocation="true"
             allowDefinition="Everywhere"/>
  </configSections>
  <Telerik.Reporting>
    <typeReferences>
        <add typeName="Telerik.Reporting.OpenAccessDataSource" assemblyName="Telerik.Reporting" publicKeyToken="a9d7983dfcc261be" />
    </typeReferences>
  </Telerik.Reporting>
</configuration>

The change and workaround are documented in the official release notes and configuration documentation:

• 2024 Q3 18.2.24.924 Release Overview - Telerik Reporting
• Basic Configuration of the Reporting Engine - Telerik Reporting

If the information doesn't help you please send me a Trace log:

• For .NET Framework - How to: Create and Initialize Trace Listeners - .NET Framework | Microsoft Learn
• For .NET - How to troubleshoot errors in ASP.NET Core projects - Telerik Reporting

Looking forward to updates from you.

Regards,
Ivet
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