Yesterday, one of our customers asked for help troubleshooting a 404 error he was getting every time he tried to access the dashboard (admin interface) of any sub-site he created and wondered if there was anything that needed to be changed server side to get it to work. I informed him that if he followed the instructions on WordPress’ Official Site, it should work without additional intervention from us. I was partially correct. Since I’ve never configured a WordPress Multi-site before, I spent more than a couple of hours going through the steps myself and indeed ran into the same problem that our customer experienced. I then scoured the web for a solution and knew it had something to do with the URL Rewrite rules but was unable to figure out a solution. Fortunately, our customer was able to find the solution himself which I will now share with you.
On line 24 (WordPress Rule 4) of the web.config markup that WordPress gives you when you click on the Network Setup link under Settings, it reads:
<action type=”Rewrite” url=”{R:1}” />
It needs to be changed to:
<action type=”Rewrite” url=”{R:2}” />
Many thanks to Lucas Nieboer for pointing out the solution!