Agent not picking up builds after upgrade to Teamcity 7

I upgraded my teamcity server and agents to 7.0.2 from 6.0.0 and after the upgrade the agent connects to the server but doesn't start running any builds. I use MySQL database.

There are warnings that appear in the teamcity-server.log file that prevent a build from starting on the server

Any help is appreciated.

[2012-04-16 18:02:03,997]   WARN -   jetbrains.buildServer.SERVER - Failed to start build: null, error: java.lang.NullPointerException
[2012-04-16 18:02:09,013]   WARN -   jetbrains.buildServer.SERVER - Failed to start build: null, error: java.lang.NullPointerException
[2012-04-16 18:02:14,024]   WARN -   jetbrains.buildServer.SERVER - Failed to start build: null, error: java.lang.NullPointerException
[2012-04-16 18:02:19,399]   WARN -   jetbrains.buildServer.SERVER - Failed to start build: null, error: java.lang.NullPointerException
[2012-04-16 18:02:24,465]   WARN -   jetbrains.buildServer.SERVER - Failed to start build: null, error: java.lang.NullPointerException
[2012-04-16 18:02:29,477]   WARN -   jetbrains.buildServer.SERVER - Failed to start build: null, error: java.lang.NullPointerException
[2012-04-16 18:02:34,488]   WARN -   jetbrains.buildServer.SERVER - Failed to start build: null, error: java.lang.NullPointerException