Troubleshoot Error Dynamics AX 2009 AOS Service not Starting

Problem: Recently while doing an upgrade from Beta > RTM > SP1, quite a few times I encountered this problem of AOS Service not ready to start.

Error #1: When I start the AOS Service, it gives me the following error, This error doesn't make that much of a sense:

Error #2: Further navigating to Event Viewer, I can see exact error,

































Solution - This happens because of the fact that database would be having a older version of the sp's which the new AOS can't execute. In my case, I was upgrading from a pre-RTM version to RTM one, So the database was a pre-RTM one, Usually it's the setup tool's responsibility to upgrade the Database when you run the AOS pointing to the old database. But, sometimes it fails to do that way. In my case, I had to restart the machine after the uninstallation of the pre-rtm bits and then again installed RTM bits and gave it a try and it worked. Same case mighthappen when you upgrade from RTM > SP1.