Weird page cannot be displayed error

[dj4uk]

I have a client that is reporting that they get "Page cannot be displayed" error messages when browsing a website I've developed. Now this only seems to be happening internally to them. When the Internet option for Showing friendly HTTP error messages is turned off things work fine?!?

Everything works fine whether this option is turned on or off here.

Can anyone shed any light on what might be causing this their end?

Cheers

Dave

[axion_sa]

Yes - it's an intermittent problem; the disabling of friendly HTTP errors will not affect how the server reacts to user input.
Check your server application event log for any unhandled exceptions (if using .NET 2.0), and/or add logging to your application & wait for the error to happen again.
Lastly - make sure you get exact steps to reproduce from the client; a "Page cannot be displayed" message isn't exactly helpful if one doesn't know how they got to that error...

[dj4uk]

Well this is the weird thing. I can reproduce the steps here and I NEVER get the error page (friendly HTTP errors on or off).

Our client can make the error page appear everytime when they do a sequence of events when friendly HTTP errors are on but when turned off they also NEVER get the error!?

So it's become virtually impossible to debug what is going on!

I did read someone that IE returns the page cannot be displayed page when an error code is returned from the server or if the response size is very small but this shouldn't be the case.

DJ

[nemaroller]

If you know which page is causing the error - (since you stated the tried the sequence of events the client did to reproduce it), I would check your IIS logs for hits on that page.

You state you cannot reproduce the error, but are you trying from your internal network only?

Perhaps a proxy server is behaving badly...

Is this an FTP site? There's a known bug in IE 5.1 -6.1 which relates to that option.

[dj4uk]

I'll get a copy of the IIS logs for yesterday and take a look!

The website is hosted remotely and I can't reproduce the error from here or other locations - it only happens when accessing from the client's network. I'll have a word with their IT to see if they are using a Proxy.

It's not an FTP site so can discount that.

Thanks for the help - will let you know what I find!

Dave

[mendhak]

I don't know if there's anyone technically competent there, but if they could examine the headers of the page returned when they get that error? If it's not a 200 OK, then IE's friendly error messages feature starts acting up, especially if the HTML being returned is rather small, because if too small IE then assumes that something wrong has happened. It's friendly after all!

[dj4uk]

Yep I've got the IIS logs now so I'll have a look!

Cheers

[dj4uk]

Ok essentially this is what is happening...

I'm using button web controls that OnClick do a Response.Redirect to a different URL. This uses a 302 redirect and it seems that when this happens on my client's network for some unknown reason this 302 is seen as an error by IE6 and the "Page cannot be displayed" message is displayed. I've tried it here on IE6 and it works fine. Also disabling friendly HTTP errors their end sorts the problem.

I've tried using a direct link to the URL rather than the Button with a postback and it works fine at my client's locaiton. However I can't replace all buttons with links as in some cases more than just the redirect are taking place.

I really need to work out why IE6 seems to treat these 302 redirects as errors when they aren't!

Help!

[mendhak]

Are the URLs very large?

[dj4uk]

No they aren't unfortunately.

It looks like it might be an issue with their Proxy server - I'm talking to their IT department currently. Will update when I know more!

[mendhak]

A proxy server giving the user a separate status code?

[nemaroller]

A poorly configured proxy server can do a lot of damage - especially to http headers. And it always annoying to solve.