Hi,

As I want to add validation during Document save, I create ContentSavingNotification as below:

    public class PageValidationNotificationHandler : INotificationHandler<ContentSavingNotification> {

Public void Handle(ContentSavingNotification notification) {
      DoSomething();
     notification.CancelOperation(
                new EventMessage(
                    "Publishing error",
                    "You cannot save this page with some reason",
                    EventMessageType.Error));
            notification.Cancel = true;
}

}

When I run it, and user click save, it work and show the error message as well. But when user can click Save and Publish Umbraco return the error as below :

Input string was not in a correct format.
Exception Details
System.FormatException, System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e: Input string was not in a correct format.

at System.Number.ThrowOverflowOrFormatException(ParsingStatus status, TypeCode type)
   at System.Int32.Parse(String s, IFormatProvider provider)
   at Umbraco.Extensions.ContentExtensions.<>c.<GetAncestorIds>b__8_1(String s)
   at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()
   at Umbraco.Cms.Web.BackOffice.Controllers.ContentController.GetPublishedCulturesFromAncestors(IContent content)
   at Umbraco.Cms.Web.BackOffice.Controllers.ContentController.AddDomainWarnings(IContent persistedContent, String[] culturesPublished, SimpleNotificationModel globalNotifications)
   at Umbraco.Cms.Web.BackOffice.Controllers.ContentController.PostSaveInternal[TVariant](ContentItemSave contentItem, Func`3 saveMethod, Func`2 mapToDisplay)
   at 

Can I know how to handle it which is not allow user save or publish the invalid page content.

Thank you