Postgres no longer starts

CentOS 5.x (now 5.8), Postgres 8.4.something. Postgres had been up and running for over a year now.

After an update on the system, and adding mod_ssl in Apache (is this related? No idea.), Postgres no longer starts up. It just fails silently. “pgstartup.log” contains only one single line:

                runuser: cannot set groups: Operation not permitted

I have no idea where to begin to debug this; Google only produces a handful of results about this error message in relation to Postgres. None fix my problem.

Whatever I do, everything just fails quietly. As far as I can see, the configuration files haven’t changed.

Help? Where do I even begin to debug this? Could a complete reinstall of Postgres and restoration of the databases help?

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                Bart.