Web admin interface returns an http 500 error with:

"Cannot parse model definitions file /etc/sipxpbx/commserver/user-settings.xml"

Look at recent sipX log files.

in /var/log/sipxpbx/sipxconfig.log, we see:

	"2017-04-03T18:22:55.165000Z":41259:JAVA:ERR:hostname.example.com:P1-18:00000000:SearchManagerImpl:"search by user query error"
	java.io.FileNotFoundException: /var/sipxdata/tmp/index/_137b.prx (Too many open files)
	[...]
	java.net.SocketException: Too many open files
	[...]
	Caused by: java.io.FileNotFoundException: /etc/sipxpbx/commserver/user-settings.xml (Too many open files)

checking how many file descriptors each process has open:

	for i in /proc/*/fd ; do echo -n "$i" ; ls -1 "$i" | wc ; done

shows a very high number for one of the processes:

	/proc/5054/fd  16383   16383   87190

associated with the process for sipXconfig:

	500      5054  4539 11 11:56 ?        00:01:00     /usr/bin/java -Dcom.ibm.tools.attach.enable=no -XX:MaxPermSize=128M -Xmx1024m -Djava.io.tmpdir=/var/sipxdata/tmp -Djetty.lib.dir=/usr/share/java/sipXecs/sipXconfig

...so we restart sipXconfig:

get the name first, since it's not 'sipXconfig':

	sudo -u sipxchange sipxproc -l | grep -i config

	{"ConfigServer"=>"Running",
	 "ConfigAgent"=>"Running",
	 "CallResolver-Agent"=>"ConfigurationMismatch",

ConfigServer looks like a good bet, restart that:

	sudo -u sipxchange sipxproc -r ConfigServer

then wait a few seconds for java to spin up, and things go back to normal.