If there are errors in the postrotate script block, where are they logged in Ubuntu?
I am pretty sure any errors are just dumped to stderr. You should be able to redirect your postrotate to a file with basic I/O redirection. I'm not sure if Ubuntu has the same file, but there should be an equivalent to the following;
Looking in my
/etc/logrotate.d/syslog, I see that the
/bin/kill command's stderr is redirected to
/dev/null. There's no reason this couldn't be changed to a regular file descriptor.
/bin/kill -HUP `cat /var/run/syslogd.pid 2> /dev/null` 2> /dev/null || true