Happened again and an import doesn't work... It is realy annoying that it happens, because it is not my code, because if i delete everything the error is still there... It is probably some kind of cache problem, but tried "Republish entire site" is still not working.... I can access the umbraco administartion without any problems.

Did you find any solution?

I have exactly the same problem. When I clear the cookies everything goes well but after some time may that happen again. 

No sadly no. I realy hope that it is not going to be a problem in production stage. Its not good :( 

I have uploaded the web site to a shared host. 

The problem is that this does not happen always. It happens only from one computer, and if cookies deleted  all run good for some time. 

I uploaded the whole site again to see if that continues happening. 

It's realy stange..

I will let you know for any progress...

thanks. I realy hope that the umbraco team find a solution for this very soon btw using 4.7 version here

I also use 4.7.2.

I am realy trying to reproduce that on another computer and I can't. Any ideas ?

Use Microsoft Deployment Tool 2.1. Remember to stop med website, because of the Umbraco Database - while you use the tool to zip it. Try that

Nothing changed. I am trying to aproach it as much as possible. 

(If that helps): After deleting cookies, everything runs well, but when I save an article or something ''Unrecognized Guid format" exception occurs.

Do you have more than one window open with a session or a cookie set... one or more windows active on the website where you are logged in ? in different browser. Might be the reason.. Looks like for me.

I also got this issue yesterday. This seems like a big ol' fashioned bug to me - can we raise it in the issue tracker. By the look of the stacktrace it looks like a lack of safety checking in the code. Not sure how cookies can affect someone on the front-end viewing a page though. Very strange.

It's a kind of bug for sure. 

Let me tell you what that did happen at the one of the computers as I told before. Something happened with some activex plugins of the browser and caused that exception. I couldn't figure out what exactly is wrong. But I cleaned up the computer with the issue, and this doesn't happen again. 

But there should be a better parsing somewhere in the code, so not to show the exception, nevertheless what happens with browser.

I am not sure if that helps, but that what happend to me. 

I have same problem, umbraco was broken on my presentation for clients, it was stoped working with errors. I have demonstrate fronthend pages this was working well, then i have go to backend and i have change some text and publish, after that site was broken and fronthend pages not shown but errors. I was stop demonstration.

In umbraco log ther was error report:

At / (Referred by: ): System.FormatException: Unrecognized Guid format. at System.Guid.GuidResult.SetFailure(ParseFailureKind failure, String failureMessageID, Object failureMessageFormatArgument, String failureArgumentName, Exception innerException) at System.Guid.TryParseGuid(String g, GuidStyles flags, GuidResult& result) at System.Guid..ctor(String g) at umbraco.presentation.UmbracoContext.GetXml() at umbraco.UmbracoDefault.Page_PreInit(Object sender, EventArgs e) at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) at System.EventHandler.Invoke(Object sender, EventArgs e) at System.Web.UI.Page.OnPreInit(EventArgs e) at System.Web.UI.Page.PerformPreInit() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

After 2 hours i was go home and try again, now site is working without errors. 

Where is the problem, i am woryed how it will working in future ? 

Version is 4.7.2 , iis 7, asp 4

is working on a reply...