TypeError: Undefined is not an object

[Robert]

We are getting this error message on the latest mac os only (Ios 12) and only on Safari. 

TypeError: null is not an object(evaluating 'document.getElementById('ctl00_PageContent_QUES_TITLERequiredFieldValidator') ['controltovalidate']="ctl00_PageContent_QUES_TITLE"')

TypeError: null is not an object (evaluationg 'b._behaviors') Telerik.web.ui.webresource.axd:6:7292

TypeError: null is not an object (evaluationg 'a.control=this') Telerik.web.ui.webresource.axd:6:7420

This does not happen on a mac using chrome nor on any browser on windows or linix.

 

Any help would be appreciated. 

 

 

[Rumen]

It would be hard to pinpoint the exact cause of the issue, however, I can suggest a couple of things to try in order to narrow the search:

• Try to disable AJAX by setting EnableAJAX property of RadAjaxPanel/RadAjaxManager to false and see if there is a server-side error thrown (see this KB for more information - Get more descriptive errors by disabling AJAX).
• Ensure that the controls are not Ajax-ified multiple times (e.g if RadAjaxManager and RadAjaxPanel are used at the same time)

If the issue persists please send us a sample runnable project where the issue is reproduced. This will enable us to investigate the problematic behavior and look for its cause.