Server renders blank page instead of report at times

[Toya]

We are having an issue with the HTML5 report viewer. At times when a report is selected instead of opening we get a blank screen. I looked at the develop tools for the browser and see the messages below, can you tell me where to look to fix this?

[Ivet]

Hi Toya,

I'm sorry to hear that you are facing an issue with our product. Thank you for sharing the screenshot of the error message.

In the latest version 19.1.25.521, we made changes to the rendering of report viewers to ensure compatibility with the Sass-based Kendo UI themes. Consequently, some CSS rules that previously worked may not function as expected in this version. If this is the case, it is essential to use updated selectors that correspond with the new HTML output of the report viewer.

In the pages below mentioned that the Kendo UI for jQuery dependency has been updated to Kendo UI for jQuery 2025.1.227, but only the latter explicitly mentions the Kendo theme that will be required with this version:

• Telerik Reporting - Progress® Telerik® Reporting 2025 Q2 (19.1.25.521)
• 2025 Q2 19.1.25.521 Release Overview - Telerik Reporting

To resolve the issue, you can use this Blank Report Viewer Screen in Version 19.1.25.521 of Telerik Reporting - Telerik Reporting KB article.

My recommendation for future updates is to always take a look at the upgrade article from the docs for that version - 2025 Q2 19.1.25.521 Release Overview - Telerik Reporting, and for any Kendo-related changes, you can also refer to the official Kendo compatibility docs - jQuery Sass Themes Compatibility - Kendo UI for jQuery.

If that doesn't help to resolve the issue, could you please send me a Trace log and Fiddler?

• Trace log for .Net - How to troubleshoot errors in ASP.NET Core projects - Telerik Reporting
• Trace log for .Net Framework - How to: Create and Initialize Trace Listeners - .NET Framework | Microsoft Learn
• Fiddler - The Ultimate Web Debugging Tool - Download Fiddler Everywhere | Telerik

I hope you will test it and keep us updated.

Regards,
Ivet
Progress Telerik

[Toya]

Thank you for your response, we are on version 19.0.25.211, I read the links you sent and the blank page we get is the whole browser window. Everything goes gray. So I think this may be different than what you are describing. Our issue is very random, you can select a report 20 or more times and it renders correctly every time, then it doesn't.

[Ivet]

It sounds like a specific scenario. For this purpose, to be more helpful, could you please send me your project and the requested logs? If you are hesitant to send your project here, you can open a ticket and provide the details there.

[Toya]

How do you send the project? I can open a ticket, just not sure how and which project files to send.

[Ivet]

To open a ticket, you can use the following article - How to Get the Most Out of the Telerik Document Processing Support - Telerik Document Processing.

To help you, I will need the whole project, or you could send me a Fiddler and Trace log.

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