ok, here's what I did Document.BeforePublish += ValidateUrlSegmentLength;

        private void ValidateUrlSegmentLength(Document sender, PublishEventArgs e)
        {
            var urlName = DocumentExtensions.GetPropertyAsString(sender, "umbracoUrlName");
            if (urlName.HasValue() == false && sender.Text.Length > 200)
            {
                e.Cancel = true;
                var page = HttpContext.Current.Handler as Page;
                if (page != null)
                {
                    page.PreRenderComplete += (s, a) => umbraco.BasePages.BasePage.Current.ClientTools.ShowSpeechBubble(
                                                            umbraco.BasePages.BasePage.speechBubbleIcon.error,
                                                            "Not Published", "Please add a shorter UrlName"
                                                        ); 
                }
            }
        }

I also added a regex validation to umbracoUrlName .{0,200}

I think this should be validated out of the box. There is already a issue for this in the issue tracker : http://issues.umbraco.org/issue/U4-1955

You can vote this up.

Voted.

Hi Can you explain how to implement this solution? do I need to inherit from "ApplicationEventHandler"? Thanks I am using umbraco version 7.1.4

Yes, see http://our.umbraco.org/documentation/Reference/Events/application-startup

Thanks I am using ver 7.1.8 and I think the problem is solved in this version. I tried really long urls an didn't get any YSOD :)

Hi I am using umbraco 7.2.1 and I got the issue again, can anyone help me with the implementation of the method above? I keep getting messages for using deprecated methods and classes this is the code:

 public class UrlValidation : ApplicationEventHandler
    {
        public void UrlValidationEvent()
        {
            Document.BeforePublish += ValidateUrlSegmentLength;
        }

        private void ValidateUrlSegmentLength(Document sender, PublishEventArgs e)
        {
            var urlName = DocumentExtensions.GetPropertyAsString(sender, "umbracoUrlName");
            if (urlName.HasValue() == false && sender.Text.Length > 200)
            {
                e.Cancel = true;
                var page = HttpContext.Current.Handler as Page;
                if (page != null)
                {
                    page.PreRenderComplete += (s, a) => umbraco.BasePages.BasePage.Current.ClientTools.ShowSpeechBubble(
                                                            umbraco.BasePages.BasePage.speechBubbleIcon.error,
                                                            "Not Published", "Please add a shorter UrlName"
                                                        );
                }
            }
        }
    }

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