Editor - Uncaught DOMException while html attributes processing if the attribute has value " on"

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Purushothama asked on 12 Jan 2022, 05:43 PM | edited on 12 Jan 2022, 06:31 PM


I'm using Kendo Editor to handle the rich text content.  We have a strange issue when the pasted html contains the attribute value with the keyword " on". Please find below the description.

  1. Copy the content from external source (I have copied form G Sheets). Please find below:

<span data-sheets-userformat="{"2":15037,"3":{"1":0},"5":{"1":[{"1":2,"2":0,"5":{"1":2,"2":0}},{"1":0,"2":0,"3":3},{"1":1,"2":0,"4":1}]},"6":{"1":[{"1":2,"2":0,"5":{"1":2,"2":0}},{"1":0,"2":0,"3":3},{"1":1,"2":0,"4":1}]},"7":{"1":[{"1":2,"2":0,"5":{"1":2,"2":0}},{"1":0,"2":0,"3":3},{"1":1,"2":0,"4":1}]},"8":{"1":[{"1":2,"2":0,"5":{"1":2,"2":0}},{"1":0,"2":0,"3":3},{"1":1,"2":0,"4":1}]},"10":2,"12":0,"14":{"1":2,"2":0},"15":"Calibri","16":11}" data-sheets-value="{"1":2,"2":"Just once"}" style="font-size:11pt;font-family:Calibri, Arial;">Just once</span><br />

  1. There is no issue while pasting the content. Pasted content displays properly.
  2. Save the form and load the data from database, there is the below issue in the browser console.

Uncaught DOMException: Failed to execute 'setAttribute' on 'Element': 'k-script-once"}"' is not a valid attribute name.

Problem appears to be in the function "_preventScriptExecution" and the statement :  this.setAttribute('k-script-' + name, attribute.value);

Note: This issue happens ONLY when we have html and the attributes are having the keyword " on" (“space” followed by text “on”)


attribute="{"key":" on"}"

data-sheets-value="{"2":"Just once"}"

I have attached the sample screenshots and the html input data.

Could you please let me know if there is a fix for this issue?

Thanks in advance for your feedback.



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Telerik team
answered on 17 Jan 2022, 05:12 PM

Hi Puru,


Thank you for writing to us.

Before discussing the technical situation, I would like to clarify something first. It seems that you are using Telerik UI for MVC and Kendo.dll assembly, but I couldn't find active license for this account regarding this product.

Could you first contact your License Representative of your company and ensure that they add your account as a Licensed Developer? Or they can also contact our Sales department for additional inquiries.

Once this is done and an active license is attached to your account, I can then fully test the mentioned behavior and suggest the proper steps to handle the technical issues.


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