[Foreman] - Application failed / How to debug passenger

Hi all,

I'm using a Katello (2.4.0) / Foreman (1.10.1) instance on Oracle Linux 6.7

I recently had a disk issue (file corruption) and had to restore my
instance. Since then the Foreman application seems to not work anymore. The
/var/log/httpd/error_log get new error every few seconds

9792 stdout]
[ 2016-03-07 11:49:50.4543 9603/7fa4d8032700 Pool2/Spawner.h:159 ]: [App
9792 stderr] Error writing to temporary file
[ 2016-03-07 11:49:50.4571 9603/7fa4d8281700 Pool2/Implementation.cpp:849 ]:
Could not spawn process for group /usr/share/foreman#default: An error
occurred while starting up the preloader. It sent an unknown response type
in 'void
std::string&, Passenger::SpawnException::ErrorKind,
Passenger::ApplicationPool2::Spawner::BackgroundIOCapturerPtr&, const
Passenger::ApplicationPool2::Spawner::DebugDirPtr&)' (SmartSpawner.h:150)
in 'std::string
in 'void Passenger::ApplicationPool2::SmartSpawner::startPreloader()' (
in 'virtual Passenger::ApplicationPool2::ProcessPtr
Passenger::ApplicationPool2::Options&)' (SmartSpawner.h:744)
in 'void Passenger::ApplicationPool2::Group::spawnThreadRealMain(const
Passenger::ApplicationPool2::SpawnerPtr&, const
Passenger::ApplicationPool2::Options&, unsigned int)' (Implementation.cpp:

[ 2016-03-07 11:49:50.4573 9603/7fa4cee1c700 agents/HelperAgent/
RequestHandler.h:1971 ]: [Client 20] Cannot checkout session. An error
occurred while starting up the preloader. It sent an unknown response type
Error page:

Error writing to temporary file

I'm not at all knowledgeable about Passenger, so I don't really have an
idea about how to debug this.

Best regards