RadCalendar - Cannot read properties of undefined (reading '_events') Error

[Shree]

Hi Team

We have removed the AjaxControlToolkit reference as it is no longer required from our solution.  However, one file, where no changes were made, is now breaking, after we removed the AjaxControlToolkit package. This file uses the Telerik RadCalendar control and is breaking during initialization.

Interestingly, the error disappears when the AjaxControlToolkit package is re-added.  The following error is noticed when toolkit package is removed ,

Uncaught TypeError: Cannot read properties of undefined (reading '_events')
    at Sys.UI.DomEvent.addHandler (Telerik.Web.UI.WebResource.axd?_TSM_HiddenField_=ctl00_rsmMain_TSM&compress=1&_TSM_CombinedScripts_=%3b%3bSystem.Web.Extensions%2c+Version%3d4.0.0.0%2c+Culture%3dneutral%2c+PublicKeyToken%3d31bf3856ad364e35%3aen-US%3a4533c2d0-c52e-4b49-a697-806d77e9914d%3aea597d4b%3ab25378d2%3bTelerik.Web.UI%2c+Version%3d2021.3.1111.40%2c+Culture%3dneutral%2c+PublicKeyToken%3d121fae78165ba3d4%3aen-US%3abcb430ee-771a-4d39-a6d4-3550d81a8d67%3a16e4e7cd%3a365331c3%3a88144a7a%3aed16cbdc%3a24ee1bba%3ab2e06756%3a92fe8ea0%3afa31b949%3ac128760b%3a19620875%3a874f8ea2%3af46195d3%3a4877f69a%3a33715776%3a490a9d4e%3abd8f85e4%3a58366029%3a2003d0b8%3a1e771326%3aaa288e2d%3a258f1c72%3ae330518b%3ac8618e41%3ae4f8f289%3a1a73651d%3a333f8d94:6:57366)
    at Telerik.Web.UI.RadCalendar.initialize (Telerik.Web.UI.WebResource.axd?_TSM_HiddenField_=ctl00_rsmMain_TSM&compress=1&_TSM_CombinedScripts_=%3b%3bTelerik.Web.UI%2c+Version%3d2021.3.1111.40%2c+Culture%3dneutral%2c+PublicKeyToken%3d121fae78165ba3d4%3aen-US%3abcb430ee-771a-4d39-a6d4-3550d81a8d67%3a59462f1%3aa51ee93e:109:8)
    at Telerik.Web.UI.RadCalendar.endUpdate (Telerik.Web.UI.WebResource.axd?_TSM_HiddenField_=ctl00_rsmMain_TSM&compress=1&_TSM_CombinedScripts_=%3b%3bSystem.Web.Extensions%2c+Version%3d4.0.0.0%2c+Culture%3dneutral%2c+PublicKeyToken%3d31bf3856ad364e35%3aen-US%3a4533c2d0-c52e-4b49-a697-806d77e9914d%3aea597d4b%3ab25378d2%3bTelerik.Web.UI%2c+Version%3d2021.3.1111.40%2c+Culture%3dneutral%2c+PublicKeyToken%3d121fae78165ba3d4%3aen-US%3abcb430ee-771a-4d39-a6d4-3550d81a8d67%3a16e4e7cd%3a365331c3%3a88144a7a%3aed16cbdc%3a24ee1bba%3ab2e06756%3a92fe8ea0%3afa31b949%3ac128760b%3a19620875%3a874f8ea2%3af46195d3%3a4877f69a%3a33715776%3a490a9d4e%3abd8f85e4%3a58366029%3a2003d0b8%3a1e771326%3aaa288e2d%3a258f1c72%3ae330518b%3ac8618e41%3ae4f8f289%3a1a73651d%3a333f8d94:6:53689)
    at Sys.Component.create (Telerik.Web.UI.WebResource.axd?_TSM_HiddenField_=ctl00_rsmMain_TSM&compress=1&_TSM_CombinedScripts_=%3b%3bSystem.Web.Extensions%2c+Version%3d4.0.0.0%2c+Culture%3dneutral%2c+PublicKeyToken%3d31bf3856ad364e35%3aen-US%3a4533c2d0-c52e-4b49-a697-806d77e9914d%3aea597d4b%3ab25378d2%3bTelerik.Web.UI%2c+Version%3d2021.3.1111.40%2c+Culture%3dneutral%2c+PublicKeyToken%3d121fae78165ba3d4%3aen-US%3abcb430ee-771a-4d39-a6d4-3550d81a8d67%3a16e4e7cd%3a365331c3%3a88144a7a%3aed16cbdc%3a24ee1bba%3ab2e06756%3a92fe8ea0%3afa31b949%3ac128760b%3a19620875%3a874f8ea2%3af46195d3%3a4877f69a%3a33715776%3a490a9d4e%3abd8f85e4%3a58366029%3a2003d0b8%3a1e771326%3aaa288e2d%3a258f1c72%3ae330518b%3ac8618e41%3ae4f8f289%3a1a73651d%3a333f8d94:6:55151)
    at <anonymous>:4:5
    at Sys._Application.add_init (Telerik.Web.UI.WebResource.axd?_TSM_HiddenField_=ctl00_rsmMain_TSM&compress=1&_TSM_CombinedScripts_=%3b%3bSystem.Web.Extensions%2c+Version%3d4.0.0.0%2c+Culture%3dneutral%2c+PublicKeyToken%3d31bf3856ad364e35%3aen-US%3a4533c2d0-c52e-4b49-a697-806d77e9914d%3aea597d4b%3ab25378d2%3bTelerik.Web.UI%2c+Version%3d2021.3.1111.40%2c+Culture%3dneutral%2c+PublicKeyToken%3d121fae78165ba3d4%3aen-US%3abcb430ee-771a-4d39-a6d4-3550d81a8d67%3a16e4e7cd%3a365331c3%3a88144a7a%3aed16cbdc%3a24ee1bba%3ab2e06756%3a92fe8ea0%3afa31b949%3ac128760b%3a19620875%3a874f8ea2%3af46195d3%3a4877f69a%3a33715776%3a490a9d4e%3abd8f85e4%3a58366029%3a2003d0b8%3a1e771326%3aaa288e2d%3a258f1c72%3ae330518b%3ac8618e41%3ae4f8f289%3a1a73651d%3a333f8d94:6:67025)
    at <anonymous>:1:17
    at Sys._ScriptLoader._loadScriptsInternal (Telerik.Web.UI.WebResource.axd?_TSM_HiddenField_=ctl00_rsmMain_TSM&compress=1&_TSM_CombinedScripts_=%3b%3bSystem.Web.Extensions%2c+Version%3d4.0.0.0%2c+Culture%3dneutral%2c+PublicKeyToken%3d31bf3856ad364e35%3aen-US%3a4533c2d0-c52e-4b49-a697-806d77e9914d%3aea597d4b%3ab25378d2%3bTelerik.Web.UI%2c+Version%3d2021.3.1111.40%2c+Culture%3dneutral%2c+PublicKeyToken%3d121fae78165ba3d4%3aen-US%3abcb430ee-771a-4d39-a6d4-3550d81a8d67%3a16e4e7cd%3a365331c3%3a88144a7a%3aed16cbdc%3a24ee1bba%3ab2e06756%3a92fe8ea0%3afa31b949%3ac128760b%3a19620875%3a874f8ea2%3af46195d3%3a4877f69a%3a33715776%3a490a9d4e%3abd8f85e4%3a58366029%3a2003d0b8%3a1e771326%3aaa288e2d%3a258f1c72%3ae330518b%3ac8618e41%3ae4f8f289%3a1a73651d%3a333f8d94:15:4736)
    at Sys._ScriptLoader._loadScriptsInternal (Telerik.Web.UI.WebResource.axd?_TSM_HiddenField_=ctl00_rsmMain_TSM&compress=1&_TSM_CombinedScripts_=%3b%3bSystem.Web.Extensions%2c+Version%3d4.0.0.0%2c+Culture%3dneutral%2c+PublicKeyToken%3d31bf3856ad364e35%3aen-US%3a4533c2d0-c52e-4b49-a697-806d77e9914d%3aea597d4b%3ab25378d2%3bTelerik.Web.UI%2c+Version%3d2021.3.1111.40%2c+Culture%3dneutral%2c+PublicKeyToken%3d121fae78165ba3d4%3aen-US%3abcb430ee-771a-4d39-a6d4-3550d81a8d67%3a16e4e7cd%3a365331c3%3a88144a7a%3aed16cbdc%3a24ee1bba%3ab2e06756%3a92fe8ea0%3afa31b949%3ac128760b%3a19620875%3a874f8ea2%3af46195d3%3a4877f69a%3a33715776%3a490a9d4e%3abd8f85e4%3a58366029%3a2003d0b8%3a1e771326%3aaa288e2d%3a258f1c72%3ae330518b%3ac8618e41%3ae4f8f289%3a1a73651d%3a333f8d94:15:4794)
    at Sys._ScriptLoader._loadScriptsInternal (Telerik.Web.UI.WebResource.axd?_TSM_HiddenField_=ctl00_rsmMain_TSM&compress=1&_TSM_CombinedScripts_=%3b%3bSystem.Web.Extensions%2c+Version%3d4.0.0.0%2c+Culture%3dneutral%2c+PublicKeyToken%3d31bf3856ad364e35%3aen-US%3a4533c2d0-c52e-4b49-a697-806d77e9914d%3aea597d4b%3ab25378d2%3bTelerik.Web.UI%2c+Version%3d2021.3.1111.40%2c+Culture%3dneutral%2c+PublicKeyToken%3d121fae78165ba3d4%3aen-US%3abcb430ee-771a-4d39-a6d4-3550d81a8d67%3a16e4e7cd%3a365331c3%3a88144a7a%3aed16cbdc%3a24ee1bba%3ab2e06756%3a92fe8ea0%3afa31b949%3ac128760b%3a19620875%3a874f8ea2%3af46195d3%3a4877f69a%3a33715776%3a490a9d4e%3abd8f85e4%3a58366029%3a2003d0b8%3a1e771326%3aaa288e2d%3a258f1c72%3ae330518b%3ac8618e41%3ae4f8f289%3a1a73651d%3a333f8d94:15:4794)

The corresponding ajax and vb file is uploaded here for review.

[Shree]

Hi Rumen,

The issue got fixed post upgrade. Thanks.

[Rumen]

Hi Shree,

This issue is known to occur in older versions of the Telerik AJAX product. To resolve it, please upgrade to the latest version, Telerik UI for ASP.NET AJAX 2024.4.1114, which offers enhanced compatibility with modern browsers and includes the latest security improvements.

Once you’ve tested the updated version, kindly let me know if the calendar issue persists. If it does, please isolate the problem in a simplified, runnable project and submit it via a support ticket for further investigation. Thank you!

Regards,
Rumen
Progress Telerik