Unable to start the Phusion Passenger watchdog?

I ran into the same problem when compiling from source, but it was intermittent, which was really frustrating (I think it has to w/ Rails environments). We couldn't use the passenger-install-apache2-module/passenger-install-nginx-module scripts, because we needed a customized nginx installation.

I finally fixed the problem by going to whatever the passenger-config --root is, then running: rake nginx.

Update February 2016 (by Passenger author):

The officially supported method to compile PassengerAgent (without also compiling Nginx, as passenger-install-nginx-module does) is with this command:

passenger-config compile-agent

Passenger 5.0.26 and later will automatically detect the error described in this StackOverflow question, and will automatically suggest running the above command.

I've just hit this error myself and struggled to find a good answer, so here's my writeup.In my setup I'm going for Ubuntu, Apache2, the latest Passenger and Rails 2.3.

1. Install Ruby and Rubygems NB: make (very) sure your gem -v is correct, if it's wrong you'll do all this twice
2. sudo gem install passenger
3. cd /usr/lib
4. wget http://rubyforge.org/frs/download.php/76005/passenger-3.0.12.tar.gz
5. tar zxvf passenger-3.0.12.tar.gz
6. cd passenger-3.0.12
7. ./bin/passenger-install-apache2-module
8. Add export PATH=/var/lib/gems/1.8/bin:$PATH to ~/.bashrc
9. ln -s /usr/lib/passenger-3.0.12 /usr/share/phusion-passenger # => this fixes a world of hurt to do with PassengerWatchdog. NB: PassengerWatchdog doesn't come down with apt-get which is why we grabbed the binaries.
10. ln -s /usr/lib/passenger-3.0.12 /usr/lib/phusion-passenger # => similar issues.

This is from memory following thrashing it through for the last day and a half, I'll tidy up when I have to go through it again.

Try to install passenger module by running script passenger-install-apache2-module .I had same problem but on nginx; I installed passenger via gem and then recompiled nginx manually with passenger module - this caused error described by you. After running passenger-install-nginx-module such error disappeared.