Event signposts component

Exception message: String "{
  "layout": {
    "Umbraco.BlockList": [
      {
        "contentUdi": "umb://element/ff303994be7a4fe29a3de69bf4a8ec8d"
      }" is not a valid udi.<br /><br />Stack trace:    at Umbraco.Cms.Core.UdiParser.ParseInternal(String s, Boolean tryParse, Boolean knownTypes, Udi& udi)
   at Umbraco.Cms.Core.UdiParser.Parse(String s)
   at System.Linq.Enumerable.SelectArrayIterator`2.Fill(ReadOnlySpan`1 source, Span`1 destination, Func`2 func)
   at System.Linq.Enumerable.SelectArrayIterator`2.ToArray()
   at Umbraco.Cms.Core.PropertyEditors.ValueConverters.MultiNodeTreePickerValueConverter.ConvertSourceToIntermediate(IPublishedElement owner, IPublishedPropertyType propertyType, Object source, Boolean preview)
   at Umbraco.Cms.Core.PublishedCache.PublishedElementPropertyBase.GetValue(String culture, String segment)
   at Umbraco.Extensions.PublishedPropertyExtension.Value[T](IPublishedProperty property, IPublishedValueFallback publishedValueFallback, String culture, String segment, Fallback fallback, T defaultValue)
   at Umbraco.Extensions.PublishedElementExtensions.Value[T](IPublishedElement content, IPublishedValueFallback publishedValueFallback, String alias, String culture, String segment, Fallback fallback, T defaultValue)
   at Umbraco.Cms.Web.Common.PublishedModels.EventSignposts.get_Items() in /tmp/8de8ab56b4f70a5/SocialBite.Web/umbraco/models/EventSignposts.generated.cs:line 65
   at AspNetCore.Views_Partials_ContentBlocks_eventSignposts.ExecuteAsync() in /home/site/wwwroot/Views/Partials/ContentBlocks/eventSignposts.cshtml:line 13
   at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageCoreAsync(IRazorPage page, ViewContext context)
   at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderPageAsync(IRazorPage page, ViewContext context, Boolean invokeViewStarts)
   at Microsoft.AspNetCore.Mvc.Razor.RazorView.RenderAsync(ViewContext context)
   at Microsoft.AspNetCore.Mvc.ViewFeatures.HtmlHelper.RenderPartialCoreAsync(String partialViewName, Object model, ViewDataDictionary viewData, TextWriter writer)
   at Microsoft.AspNetCore.Mvc.ViewFeatures.HtmlHelper.PartialAsync(String partialViewName, Object model, ViewDataDictionary viewData)
   at AspNetCore.Views_Partials_ContentBlocks_Default.ExecuteAsync() in /home/site/wwwroot/Views/Partials/ContentBlocks/Default.cshtml:line 20<br /><br />