I am getting following error in SharePoint 2013 when I try to access DispForm.aspx of a custom list.

Error during serialization or deserialization using the JSON JavaScriptSerializer

I found two solutions but problem is I am unable to find the setting they are talking about.

Solution 1
Changing the Webpart setting CSR Render Mode to Server Render.
From where do I find this setting? I am unable to open the DispForm.aspx page in browser so how I can open webpart setting?

Solution 2
Add UseLegacyForm="TRUE" attribute in <Form tag of DispForm.aspx.
I opened DispForm.aspx in SharePoint Designer but there is no such thing as <Form so where do I change this setting?

1 Answer 1


For Solution 1: List->Form Web Parts (in the ribbon) - > Default Display Form -> then Edit Web Part Under the Miscellaneous category, you would see CSR render Mode

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For more information see here

For Solution 2

[form] element is in the Maser Page

<form runat="server" onsubmit="if (typeof(_spFormOnSubmitWrapper) != 'undefined') {return _spFormOnSubmitWrapper();} else {return true;}">

  • When trying solution 1, I am getting same error when I click on Default Display Form in Form Web Parts in ribbon. For solution 2 I am not sure if this is the right form. Because if you take a look at the solution provided here https://www.keapoint.com/workaround-the-length-of-the-string-exceeds-the-value-set-on-the-maxjsonlength-property-in-sharepoint-2013-list-forms/ the form element is different. Oct 20, 2020 at 15:47
  • Your Display Form might have got corrupted if you had opened it in the Designer, and for some reason it got updated. It's not recommended to make changes to the original forms, but make a copy of it and then make changes. Oct 20, 2020 at 15:54

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