HowTo: Avoid the Loopback check

When you work on an Essence Portal in combination with Exact Synergy Enterprise, you might run into a strange error. Where you can sign in to the Silver Webservice with your Windows credentials. But when you enter exactly the same credentials in the Essence Webservice test-page, you get a sign-in error, or an error that points to the authentication scheme. So how can it be that your credentials both work and don't work at the same time? Find out about this Schrödinger-like dillema in this blogpost.

About the situation

This problem occurs when you work with the Essence Portal and Exact Synergy Enterprise on the same server. In particular, this occurs when you have both the Essence Portal and Exact Synergy Enterprise running as separate websites under the same IIS web-server. In this case you will have to access the different applications through their external URL. Which in turn would require a modification to the Windows Hosts file.

The problem at hand

Assuming you did a correct installation of both the Essence Portal and Exact Synergy Enterprise. And enabled the Silver Webservice for Exact according to the instructions from our Productblog, and everything is up-and-running. At that point you should have checked if you could access the ESEDomain.svc where you had to enter your Windows Username and Password.

Then comes the point where you should test the Silver Webservice for Exact, using the available Test Tool which is described on our Productblog. Here you will encounter the problem that the correct Username and Password will not work.

Here's the problem, and the solution

The issue at hand is a known Windows error that also occurs in similar configurations with Microsoft Sharepoint. The problem is that Windows finds it suspicious that user credentials are used whereas both websites are running on the same server, using application pools that have users in the same domain. Therefor, Windows qualifies a valid login as an invalid login.

The solution is to disable this Loopback check, which can be done only through a Register hack. Using the Registry Editor, locate and then click the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa

Create the value DisableLoopbackCheck and enter 1 in the Value data box, and then click OK

After this, the login from the test page should be successful and a test Request should have been created in Exact Synergy Enterprise. Once your test is successful, use this information to create or modify your Enterprise Domain in the Silver Editor.