People picker not working – it does not find any users

We have noticed a weird behavior, it is very rare scenario we ran into, silly us, it was quite hard to figure out what was going on so I thought I will share it here 🙂

Scenario: We have test SharePoint 2010 farm, all configured and working, user profile synchronization working, profiles imported, we can apply security to users on portal site, we can pick them from people picker.

We go to User profil service application and we want to change Manager for one of the profiles. We type known existing user but people picker control does not resolve the user.

Another day, we did not have troubles with this operation:

What has changed, what broke???

As it come up, we were accessing Central admin site through wrong URL!!!

Lets assume we have Central admin site on address http://servername:port/ We have created another web application for portal site and assigned hostheader to it so we will be able to access portal as http://portalname. This is test environment, so for simplicity, we edited hosts file to map this “portalname” to localhost. Without thinking, we browsed Central admin site by url: http://portalname:port. Surprisingly, it works, you can access Administration. But people picker will not work.