Instance validation error: ' None ' is not a valid value for FrameType

I was making few UI changes to my SharePoint masterpage and I started getting following error, I also tried to restore previous versions of masterpage but that didnt work.
Can anyone help please.
In the error it says :

One of the properties of the Web Part has an incorrect format. Microsoft SharePoint Foundation cannot deserialize the Web Part.  Check the format of the properties and try again.]

but how I find which webpart has issue ?
My environment is SharePoint 2016.

Thanks in advance.

Server Error in '/' Application.

Instance validation error: '
                                            None
                                        ' is not a valid value for FrameType. 
  Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

 Exception Details: System.InvalidOperationException: Instance validation error: '
                                            None
                                        ' is not a valid value for FrameType.

Source Error: 


 An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.  

Stack Trace: 



[InvalidOperationException: Instance validation error: '
                                            None
                                        ' is not a valid value for FrameType.]
   Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationReaderContentEditorWebPart.Read7_FrameType(String s) +223
   Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationReaderContentEditorWebPart.Read12_ContentEditorWebPart(Boolean isNullable, Boolean checkType) +710
   Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationReaderContentEditorWebPart.Read13_WebPart() +119

[InvalidOperationException: There is an error in XML document (9, 53).]
   System.Xml.Serialization.XmlSerializer.Deserialize(XmlReader xmlReader, String encodingStyle, XmlDeserializationEvents events) +819
   Microsoft.SharePoint.WebPartPages.WebPart.ParseXml(XmlReader reader, Type type, String[] links, SPWeb spWeb) +210

[WebPartPageUserException: One of the properties of the Web Part has an incorrect format. Microsoft SharePoint Foundation cannot deserialize the Web Part.  Check the format of the properties and try again.]
   Microsoft.SharePoint.WebPartPages.WebPart.ParseXml(XmlReader reader, Type type, String[] links, SPWeb spWeb) +800
   Microsoft.SharePoint.WebPartPages.WebPart.AddParsedSubObject(Object obj) +1268
   System.Web.UI.ControlBuilder.BuildChildren(Object parentObj) +1067
   System.Web.UI.ControlBuilder.InitObject(Object obj) +479
   System.Web.UI.ControlBuilder.BuildObjectInternal() +285
   System.Web.UI.ControlBuilder.BuildChildren(Object parentObj) +888
   System.Web.UI.ControlBuilder.InitObject(Object obj) +479
   System.Web.UI.ControlBuilder.BuildObjectInternal() +285
   System.Web.UI.ControlBuilder.BuildChildren(Object parentObj) +888
   System.Web.UI.ControlBuilder.InitObject(Object obj) +479
   System.Web.UI.ControlBuilder.BuildObjectInternal() +285
   System.Web.UI.ControlBuilder.BuildChildren(Object parentObj) +888
   System.Web.UI.ControlBuilder.InitObject(Object obj) +479
   System.Web.UI.FileLevelPageControlBuilder.InitObject(Object obj) +42
   System.Web.Compilation.BuildResultNoCompileTemplateControl.FrameworkInitialize(TemplateControl templateControl) +168
   System.Web.UI.TemplateControl.FrameworkInitialize() +106
   System.Web.UI.MasterPage.CreateMaster(TemplateControl owner, HttpContext context, VirtualPath masterPageFile, IDictionary contentTemplateCollection) +1247
   System.Web.UI.Page.get_Master() +65
   System.Web.UI.Page.ApplyMasterPage() +17
   System.Web.UI.Page.PerformPreInit() +53
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1132