Cannot use Open with Explorer in a SharePoint library – solved. (“Your client does not support opening this list with Windows Explorer”)

The problem.

When browsing in a SharePoint document library, there is an option on the ribbon bar to Open with Explorer.  This is very exciting because you could copy and paste multiple files into SharePoint or move them from one folder to another.  When clicking on this button you get “Your client does not support opening this list with Windows Explorer”.

The solution.

The solution is to add a registry entry.  The root problem is that in this situation, your credentials are not passed when the target URL has a dot in the address.  The following procedure, from this Microsoft article describes how to fix things:

1. Click Start, type regedit in the Start Search box, and then press ENTER.
2. Locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WebClient\Parameters
3. On the Edit menu, point to New, and then click Multi-String Value.
4. Type AuthForwardServerList, and then press ENTER.
5. On the Edit menu, click Modify.
6. In the Value data box, type the URL of the server that hosts the Web share, and then click OK.
   Note   You can also type a list of URLs in the Value data box. For more information, see the “Sample URL list” section in this article.
7. Exit Registry Editor.