Phusion Passenger internal server error

Question

I'm using Apache + Passenger on my Linode server, with a Postgresql-9.4 database. Every so often, I get the following error, but it is unpredictable and rights itself a few minutes later with no actions taken, so it is extremely hard to debug:

Internal server error
Phusion Passenger has listed more information about the error below.
An error occurred while starting the web application. It sent an unknown response type "".

Has anyone else run into an error like this, or know what it could imply?

Chromo

Memory issues? What's the size of your Linode and is there any free memory left when you get this error? – Hoarse

@Hoarse My linode has 0.5 gb of RAM. There's no Swap Memory left when I get an error, but there is usually around 20000k Memory left. Which is odd, because I thought Memory ran out first, and Swap acted as a backup... – Chromo

It's possible the kernel reserves some memory so the system doesn't crash, but you obviously have no memory left for applications once you've reach the bottom of the swap. Anyway, even if your applications were able to use the remaining 20MB, it's not much at all and you'll run into some major problems sooner or later. Try increasing the swap as a test (even tho Linodes run on SSDs and it won't be as terribly slow as if you were swapping on an hard drive, you should consider getting more memory) and see if the error goes away, or happens less often. – Hoarse

Answer 1

Firstly go through this question, as it might solve your problem:

Passenger: internal server error

There are possible causes of problems listed here:

https://github.com/phusion/passenger/wiki/Debugging-application-startup-problems

Starspangled