Hi! Ive got a lots of these in my log... every now and then... where should i start looking? is it our legacy properties from dynamic properties, is that history now?

Episerver cms 8.11, commerce 8:15, webforms

Error instantiating property
System.ArgumentNullException: Value cannot be null.
Parameter name: templateControl
   at EPiServer.Web.TemplateControlLoader.LoadControl(HttpContextBase httpContext, Type renderType, Object renderData, TemplateControl templateControl, String tag, IDictionary`2 renderSettings, Action`2 bindDataAction)
   at EPiServer.Core.PropertyControlClassFactory.CreatePropertyControl(PropertyData propertyData, HttpContextBase httpContext, TemplateControl templateControl, String tag)
   at EPiServer.DynamicContent.PlugIn.DynamicPageProperty.<>c__DisplayClass1.b__0(PropertyData p)
   at EPiServer.DynamicContent.PlugIn.DynamicPageProperty.CreatePropertyObject(Action`1 action)System.ArgumentNullException: Value cannot be null.
Parameter name: templateControl
   at EPiServer.Web.TemplateControlLoader.LoadControl(HttpContextBase httpContext, Type renderType, Object renderData, TemplateControl templateControl, String tag, IDictionary`2 renderSettings, Action`2 bindDataAction)
   at EPiServer.Core.PropertyControlClassFactory.CreatePropertyControl(PropertyData propertyData, HttpContextBase httpContext, TemplateControl templateControl, String tag)
   at EPiServer.DynamicContent.PlugIn.DynamicPageProperty.<>c__DisplayClass1.b__0(PropertyData p)
   at EPiServer.DynamicContent.PlugIn.DynamicPageProperty.CreatePropertyObject(Action`1 action)