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One of our clients is having an issue where POSTBACK seems to be broken when they connect to our Sharepoint application.

When they navigate to a URL, an erroneous query string gets appended to the URL, so the end of the URL becomes:


this isn't something that appears on any other clients computers or ours internally. This is the only difference and it seems to be breaking their pages.

I had a quick Google and it seems that it's to do with a Microsoft ISA server, but I have no experience with that.

Is this a bug or setting on their ISA server?

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This usually happens when you are Pre-Authenticating with ISA/TMG – MichelZ Jun 24 '14 at 14:04

We've noticed the same thing with our ISA appending the same AuthResend parameter at the end of the URL. And, like you, the website doesn't work as expected. Is your SharePoint application authenticated with Forms Based or some other method? In our case, there's NTLM on the actual IIS level and then an LDAP lookup form behind it. Internally, as you're using NTLM anyway, the LDAP lookup is able to find you and you never actually see the login. Externally, I suspect the AuthResend is being appended because ISA sees that we not only have the NTLM to get through but also another authentication behind it (in our case, LDAP). So ISA is basically telling itself to send the authentication twice.

Also, are you using the same URL name internally as externally or are you using different ones and relying on Alternate Access Mappings? We have different names and I believe our issue was caused by that. As soon as we used the same name, the AuthResend went away and everything worked correctly.


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