ArcGIS Web Adaptor: Error 2878 On the dialog WebSiteList the control ListBox1 has a possible value... This is an invalid or duplicate value

Error Message

While installing the Web Adaptor it displays the following error:

"Error 2878: On the dialog WebSiteList the control ListBox1 has a possible value: Default Web Site, 80,1. This is an invalid or duplicate value."

This workaround installs the ArcGIS Web Adaptor normally. It is also possible to run the Web Adaptor install silently from the command line to work around this issue. If it is preferred to install the Web Adaptor silently rather than change settings in IIS, please see the Related Information section at the end of this article.

Cause

The issue occurs when there are multiple bindings on the same port on a single web site in IIS, or there is multiple web sites with the same port binding. The Web Adaptor installer fails to complete and returns the error.

Solution or Workaround

To workaround this issue, the existing port bindings can be removed or edited and then changed back after the install is complete.

1. Open the IIS Manager:
   1. Open the Control Panel.
   2. Click Administrative Tools.
   3. Click Internet Information Services (IIS) Manager.
2. In IIS Manager:
   1. Expand the machine on the left panel.
   2. Expand Sites.
   3. Left-click Default Web Site.
3. On the right side of the window left-click the Bindings. and a new window opens called Site Bindings. Look down the list in the new window for any bindings on the same port number. Take note of the Site Bindings settings. It may be necessary to put any changed or removed bindings back as they were after the install is completed.
4. Select any bindings with the same port number and change them to a different port or remove them.

Note:
 After the Web Adaptor install is complete these can be changed back.

To remove the binding:

1. Left-click the binding in the list.
2. Click Remove to delete the binding.

To edit the binding:

1. Left-click the binding in the list.
2. Left-click Edit.
3. Enter a different port.
4. Click OK.
5. Click the Close button to close the Site Bindings window.

If there are any other web sites, repeat Steps 2 through 4 to make sure that there are no duplicate bindings with the same port number and that the different sites don't have any bindings on the same port number as another site.

Complete the install of the Web Adaptor. There should be no error during install. If there is an error, repeat Steps 2 through 5 and verify that no two sites have the same bindings and that no site has multiple bindings on the same port.

If necessary, go back into IIS Manager and change the port bindings back to their previous state.