Postback not working on pages where Telerik Ajax is in use after migrating to SP2019

[Mustafa]

We recently migrated our Portal solution from SP2016 to SP2019. After migration we noted that Postback did not work on pages where 
Telerik is in use e.g, RadAjax, RadCombobox, or RadGrid. We are using Telerik.Web.UI Version=2019.3.917.45 in web.config. 

Page loaded successfully with all the Telerik controls and data in place. But after any click event on any of Telerik controls, The postback did not occur and blank page shows up.

It's very weired because same version is working fine in SP2016 (postback works fine) but not in SP2019. What should we do?

Can you please give us some hint, what's wrong ?

This is what we are using in Web.config

<add tagPrefix="telerik" assembly="Telerik.Web.UI, Version=2019.3.917.45, Culture=neutral, PublicKeyToken=121fae78165ba3d4" namespace="Telerik.Web.UI" />
<add name="Telerik.Web.UI.DialogHandler.aspx_*" path="Telerik.Web.UI.DialogHandler.axd" verb="*" type="Telerik.Web.UI.DialogHandler, Telerik.Web.UI, Version=2019.3.917.45, Culture=neutral, PublicKeyToken=121fae78165ba3d4" preCondition="integratedMode" />
<add name="Telerik.Web.UI.WebResource.axd_*" path="Telerik.Web.UI.WebResource.axd" verb="*" type="Telerik.Web.UI.WebResource, Telerik.Web.UI, Version=2019.3.917.45, Culture=neutral, PublicKeyToken=121fae78165ba3d4" preCondition="integratedMode" />
<add name="Telerik_Web_UI_WebResource_axd" verb="*" preCondition="integratedMode" path="Telerik.Web.UI.WebResource.axd" type="Telerik.Web.UI.WebResource" />
<add name="Telerik_Web_UI_DialogHandler_aspx" verb="*" preCondition="integratedMode" path="Telerik.Web.UI.DialogHandler.aspx" type="Telerik.Web.UI.DialogHandler" />

 

[Attila Antal]

Hi Mustafa,

This is a known bug that showed up in the latest version of SharePoint, see RadAjaxManager or RadAjaxPanel causes a Blank page on partial PostBack SharePoint 2019. It is now under investigation and a fix is expected to be delivered once the investigation is over.

Until a fix will be released, we can offer a workaround that we have shared in the comment section of the Bug Report. 

Kind regards,
Attila Antal
Progress Telerik