postgres 8.4.20
With these settings, the daemon starts :
postgresql.conf
shared_preload_libraries = 'auto_explain'
With these settings, the daemon doesn't start :
postgresql.conf
shared_preload_libraries = 'auto_explain'
auto_explain.log_min_duration = 1000
It is a server with a legacy application, so we cannot upgrade PG. I cannot find documentation of this behaviour / bug...