Hello,
I'm upgrading a .NET Framework application to the latest Telerik.Reporting assembly. We have one report which now fails to load and instead displays the broken form seen below. This form is not part of our report at all.
This error is also accompanied by an exception from within the telerikReportViewer file "TypeError: Cannot read properties of undefined (reading 'wrapper')".
I have no idea how to even begin troubleshooting this. Any suggestions? Thanks!
1 Answer, 1 is accepted
Hello Ryan,
Thank you for the screenshot and the additional information!
The error seems to be client-side, which could mean that one or more of the HTML5 Report Viewer's dependencies haven't been updated. The main things to look at are the Kendo UI for jQuery subset loaded in the application and the Kendo theme.
The version of Kendo UI for jQuery that we use in the latest release is Kendo UI for jQuery 2025.4.1111 (2025 Q4). On the page with the report viewer, in the browser console, run the command kendo.version. It will return a string with the version of kendo, and it should return 2025.4.1111 or higher. Older versions are not supported in that release of Reporting.
The required version of the Kendo SASS themes is 12.2.x/12.3.0 - jQuery Sass Themes Compatibility - Kendo UI for jQuery. You can use the sample CDN link from step 7 in the Telerik Reporting Displaying Reports Web Application HTML5 ASP.NET Web Forms Report Viewer Manual Setup - Telerik Reporting article to test.
Additionally, check if the telerikReportViewer JS file is loaded with the new version. Sometimes the browser may cache the file. A hard refresh on the page with the report viewer is recommended to avoid using the cache.
I hope that the provided information and suggestions will help. If you need further assistance, please share the code of your pages setup, so that I can see what scripts and stylesheets are referenced
Regards,
Dimitar
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