Openfire Admin Console - HTTP ERROR: 503

Hi,

I have my Openfire 3.3.3 running on Ubuntu Linux 6.10 with Java build 1.6.0-b105 and everything was working fine (inclusive of the admin console) before I upgraded to Openfire 3.5.1

After I upgraded to Openfire 3.5.1, I cannot open my admin console (http://server_address:9090) anymore and it keeps on showing me the following:-

HTTP ERROR: 503SERVICE_UNAVAILABLE

RequestURI=/

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Please help me.

Thank you