mod_jk - Unable to get the free endpoint

Im using Apache/2.2.14 (Worker MPM) + libapache2-mod-jk 1.2.28-2 + tomcat 6.0.24 for my app to work with CGI and Java, together on a single machine. I am experiencing an issue with mod_jk (I'm not sure):

Error

Internal Server Error
[info] "ajp_get_endpoint::jk_ajp_common.c (3001): Unable to get the free endpoint for worker ajp13 from 10 slots" 
[error] jk_handler::mod_jk.c (2549): Could not get endpoint for worker=ajp13

This is only happening, when I am using a remote Proxy server. Direct connections seem to be working.

jk_workers.properties:

worker.list=ajp13
worker.ajp13.type=ajp13
worker.ajp13.host=localhost
worker.ajp13.port=8009
worker.ajp13.lbfactor=50
worker.ajp13.cachesize=10
worker.ajp13.cache_timeout=600
worker.ajp13.socket_keepalive=1

mods-enabled/jk.conf

JkWorkersFile /etc/apache2/jk_workers.properties
JkLogFile /var/log/apache2/mod_jk.log
JkLogLevel info
JkLogStampFormat "[%a %b %d %H:%M:%S %Y]"
JkOptions +ForwardKeySize +ForwardURICompat -ForwardDirectories
JkRequestLogFormat "%w %V %T"
JkShmFile /var/log/apache2/jk-runtime-status

Solution

Try to remove the deprecated cachesize property and test it again.