Today I upgraded my macbook by doing so much effort (thanks to apple for making me download new 5.6 GB sized OS several times) to OS X Mavericks and after updating, what I found was my local dev environment was broken. 

Apache had stopped working. I tried to find issues with it. After sometime, I found that it changed my httpd.conf file present in /etc/apache2The original file had been renamed to httpd.conf.pre-update.

I restored the previous httpd.conf file in /etc/apache. I restarted the server with apachectl restart and it not still worked.

After that I tried to debug the problem by running apachectl -t 
httpd: Syntax error on line 502 of /private/etc/apache2/httpd.conf: Cannot load /usr/libexec/apache2/ into server: dlopen(/usr/libexec/apache2/, 10): image not found
It also removed my module file from /usr/libexec/apache2. I fixed that.
Evething works fine now.