HTC TyTNI have been trying to setup my HTC TyTN to get the synchronization to work over the air using 3G or Wifi so I’m really connected to work 24/7 :-) After setting up the Exchange 2003 servers using the excellent step-by-step guide on TechNet for this purpose I was ready to test it all.

But I ran into trouble directly and the ActiveSync reported an error: 0x80072F0D - invalid certificate. No problem, just install it to the trusted certificate store on the Windows Mobile phone…I thought. But the problem is that it’s not that easy done. After some googling I ran into Ant Drewery’s entry Windows Mobile 5.0 & ActiveSync which discussed this problem. I used his method to install the certificate into the Windows Mobile phone and it worked fine, after some initial trouble. I made the mistake first and tried to install the certificate that you get from the padlock icon, which will not work. You have to get it from the Trusted Root Certificate Store or from your administrator (which should have a backup of the original certificate installed on the OWA IIS).