An exceptionCaught() event was fired... Too many open files

My Traccar Server is down, the first thing that I did was to check the log, it shows this:

WARN: An exceptionCaught() event was fired, and it reached at the tail of the pipeline. It usually means the last handler in the pipeline did not handle the exception. - Too many open files - IOException (...)

I have increased the limits for connections and things like that.
These are some commands and result:

COMMAND: ulimit -Hn
RESULT: 50000

COMMAND: ulimit -Sn
RESULT: 50000

COMMAND: ulimit -a
RESULT:
core file size                                   (blocks, -c) 0
data seg size                                  (kbytes, -d) unlimited
scheduling priority                         (-e) 0
file size                                            (blocks, -f) unlimited
pending signals                              (-i) 3892
max locked memory                      (kbytes, -l) 64
max memory size                           (kbytes, -m) unlimited
open files                                        (-n) 50000
pipe size                                         (512 bytes, -p) 8
POSIX message queues               (bytes, -q) 819200
real-time priority                            (-r) 0
stack size                                       (kbytes, -s) 8192
cpu time                                         (seconds, -t) unlimited
max user processes                      (-u) 3892
virtual memory                               (kbytes, -v) unlimited
file locks                                          (-x) unlimited

COMMAND: netstat -ant | awk '{print $6}' | sort | uniq -c | sort -n
RESULT:
1           established)
1           Foreign
1           SYN_RECV
10        TIME_WAIT
120      CLOSE_WAIT
188      LISTEN
3756   ESTABLISHED

COMMAND: netstat -an | grep :5027 | wc -l
RESULT: 3857

COMMAND: sudo cat /proc/sys/fs/file-max
RESULT: 99102

COMMAND: sudo lsof | grep java | wc -l
RESULT: 8586

COMMAND: free -h
RESULT:
                    total     used     free     shared     buff/cache     available
Mem:          994M   492M    122M     44M     379M              296M
Swap:          1.0G     362M    661M

When the server has a lot of connections opened this goes down.
I think the most obvious would be that the server don't accept more connections and keep working, but no, the server die.

How can I avoid this? I found this link:
https://github.com/netty/netty/issues/1578

I hope you help.

Best Regards
Peter

Check process limits and actual number of connections.

Are you talking about this?

top

sudo cat /proc/515/limits

Yes, so it's 4k limit, not 50k.

Anton, I know have you seen my post, but, could you take another check to the results of the commands, mainly commands ulimit.

Best Regards
Peter

I have read it again and I don't understand what you want me to see.

Also, I don't understand what you mean by "but no, the server die". Server continues running, as far as I can tell.

No, when the number of connections reach the max number, the app crash.
When I said "server die" I was talking about the app.

So did you execute all those commands before server died?

Yes, when the app wasn't working and the max number of connection was reached.
All that commands were executed before to restart server.

And it died after that?

The server don't die. The app crash.

OK, please provide some evidence of the crash, exit code, system logs etc.

Commands executed this moment:

COMMAND: who
RESULT: admin pts/0 2019-03-09 19:01 (xxx.xxx.xxx.xxx)

COMMAND: su root --shell /bin/bash --command "ulimit -n"
RESULT: 1024

Did you see this link?

https://github.com/netty/netty/issues/1578

Yes, I saw the link.