If you are running chrooted lighttpd web server, upgrade procedure is a bit tricky. You need to upgrade webserver, as well as php and related extensions.

Following is common sequence you need to follow. I am just going to write down all steps, followed by actual Linux commands. If you need detailed instructions, please see how to install and configure lighttpd in chrooted jail.

Step # 1: Stop or shutdown lighttpd web server
# /etc/init.d/lighttpd stop

Step # 2: Backup existing chrooted directory (such as /webroot) to another partition or directory:
# mkdir /root/old.lighttpd
# tar -zcvf /root/old.lighttpd/webroot.tar.gz /webroot


Step # 3: Download latest lighttpd. Upgrade lighttpd using rpm:
# rpm -Uvh lighttpd*
Or using apt-get
# apt-get update; apt-get install lighttpd
Or using source code installation (make sure you use old ./configure syntax)
# ./configure
# make
# make install
Now upgrade PHP and php-mysql extensions using rpm or apt-get commands.
# rpm php*
OR
# apt-get php4-cgi php4-mysql

Step # 4: Now upgrade chrooted lighttpd which is located at /webroot:
# cd /webroot
# rm -rf usr
# rm -rf lib
# cp /usr/bin/php4-cgi /webroot/usr/bin/
# cp /usr/bin/php4 /webroot/usr/bin/
# /bin/l2chroot /usr/bin/php4
# /bin/l2chroot /usr/bin/php4-cgi
# cp /lib/ld-linux.so.2 /webroot/lib

Copy mysql extnsion
# cp /usr/lib/php4/20060606/mysql.so /webroot/usr/lib/php4/20060606/

Repeat above procedure to copy all your php shared modules such as php-imap, php-gd, php-memcache etc.

Step # 5: Now Start lighttpd:
# /etc/init.d/lighttpd start

Step # 6:Make sure everything is working perfectly:
# tail -f /var/log/message
# netstat -tulpn


Make sure you copy other essentials file such as /usr/sbin/sendmail (or mini_sendmail) to chrooted jail.