Hello Ravi,

I have converted your message from the Attempt by security transparent method 'Telerik.Reporting.OpenXmlRendering.Spreadsheet.Workbook..ctor()' to access security critical method thread to a new bug report, as it seems to be related to the `Telerik.Reporting.dll`, instead of `Telerik.Reporting.OpenXmlRendering.2.7.2.dll` the original issue was related to.

Generally, these types of issues occur when the Telerik.Reporting assembly that targets .NET Standard 2.0 is used in a .NET Framework project. The .NET Standard 2.0 assembly is marked with "AllowPartiallyTrustedCallersAttribute", whereas the one that references .NET Framework does not have this flag set.

If this is indeed the case, as a potential workaround, you may consider removing the reference to `Telerik.Reporting.dll` targeting .NET Standard 2.0 and referencing the one that targets .NET Framework instead. You can find the .NET Framework assemblies in the `Bin` folder of the installation path, for example: C:\Program Files (x86)\Progress\Telerik Reporting 2025 Q4\Bin.

I hope this helps. Please let me know if you need any further assistance with this matter.

Regards,
Petar
Progress Telerik