Environment
Product: Telerik UI for ASP.NET AJAX
Version: 2025.4.1210.462
.NET Framework: 4.8
App type: ASP.NET Web Forms
IIS: Integrated pipeline
Host path: /MyService/
Controls used: RadScriptManager, RadAjaxManager, RadGrid, RadComboBox, RadAjaxPanel, etc.
Entry page from Encompass: Validation.aspx (standalone page, not using a master page)
Telerik CDN: Disabled
RadScriptManager: EnableScriptCombine="false"
Error
When opening MyService from Encompass Desktop, users see:
An error has occurred in the script on this page.
Line: 1
Char: 173461
Error: Invalid character
Code: 0
URL: /MyService/ScriptResource.axd?d=...
What we found
When inspecting the script response, we see modern JavaScript syntax that appears incompatible with the Encompass embedded browser (IE-like engine), for example:
_renderActiveItemStyle:function(e){
var t=this.get_owner().get_id(),
i=`${t}_ActiveItemStyle`;
...
e=e.replaceAll(";"," !important;");
...
}
It looks like ES6 template literals and replaceAll() are causing a parse error in the embedded browser.
Questions
1) Is Q1 2025 officially unsupported in Internet Explorer/embedded WebBrowser-style hosts such as Encompass Desktop?
2) Is the _renderActiveItemStyle function with template literals expected in Q1 2025 RadGrid scripts?
3) Is there any supported configuration to serve IE-compatible JavaScript while staying on Q1 2025?
e.g. OutputCompression, CDN, RenderMode, legacy script bundle, etc.
4) If not, what is the recommended Telerik version for IE/embedded browser scenarios - is R3 2022 SP1 (2022.3.1109) the last supported release?
1 Answer, 1 is accepted
Hello Umer,
I hope you are doing well! Let's go over your questions one to address them accordingly
Is Q1 2025 officially unsupported in Internet Explorer/embedded WebBrowser-style hosts such as Encompass Desktop?
Yes, Telerik UI for ASP.NET AJAX Q1 2025 (2025.4.1210.462) does not officially support Internet Explorer or IE-based embedded browser environments (such as the Encompass Desktop embedded browser). The product now targets only modern browsers, and the official browser support statement is available here: http://www.telerik.com/aspnet-ajax/tech-sheets/browser-support
Is the _renderActiveItemStyle function with template literals expected in Q1 2025 RadGrid scripts?
Yes, the use of ES6+ syntax (such as template literals and methods like replaceAll()) is expected in the embedded scripts of the latest releases, including Q1 2025. This is part of the ongoing modernization of the product and is not compatible with legacy JavaScript engines found in IE-based hosts.
Is there any supported configuration to serve IE-compatible JavaScript while staying on Q1 2025?
No, there is no supported configuration or setting in Q1 2025 that will provide IE-compatible JavaScript. Options like OutputCompression, CDN, RenderMode, or script combining do not affect the ES6 syntax in the embedded scripts. There is no legacy or compatibility mode available in this release.
If not, what is the recommended Telerik version for IE/embedded browser scenarios – is R3 2022 SP1 (2022.3.1109) the last supported release?
Correct, R3 2022 SP1 (2022.3.1109) is the last version with official support for Internet Explorer and similar embedded WebBrowser controls. If your application must run in these environments, it is recommended to use R3 2022 SP1 or an earlier version. You can review the release history and browser support changes here:
I hope this information answers your questions.
Regards,
Vasko
Progress Telerik