Remote Procedure Call Error

I've got an error "Remote Procedure Call Error" when i'm refreshing the tracking web page. Have you got any idea how to fix this?

Traccar version 2.12

my.cnf for MySQL Server version: 5.5.43-0+deb7u1 (Debian):
http://pastebin.com/CYc8FSvw

traccar.cfg:
http://pastebin.com/iRsuzZub

wrapper.log
http://pastebin.com/pw8FnYMn

INFO   | jvm 1    | 2015/06/07 10:09:24 |       at java.lang.Thread.run(Thread.java:745)
INFO   | jvm 1    | 2015/06/07 10:09:29 | 2015-06-07 10:09:29.092:WARN:/:Exception while dispatching incoming RPC call
INFO   | jvm 1    | 2015/06/07 10:09:29 | com.google.gwt.user.server.rpc.UnexpectedException: Service method 'public abstract java.util.List org.traccar.web.client.model.DataService.getDevices()' threw an unexpected exception: javax.persistence.PersistenceException: org.hibernate.TransactionException: JDBC begin transaction failed: 
...
INFO   | jvm 1    | 2015/06/07 10:09:29 |       at java.lang.Thread.run(Thread.java:745)
INFO   | jvm 1    | 2015/06/07 10:09:29 | Caused by:
INFO   | jvm 1    | 2015/06/07 10:09:29 | javax.persistence.PersistenceException: org.hibernate.TransactionException: JDBC begin transaction failed:
INFO   | jvm 1    | 2015/06/07 10:09:29 |       at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1763)
INFO   | jvm 1    | 2015/06/07 10:09:29 |       at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1677)

INFO   | jvm 1    | 2015/06/07 10:09:29 | Caused by:
INFO   | jvm 1    | 2015/06/07 10:09:29 | org.hibernate.TransactionException: JDBC begin transaction failed: 
...
INFO   | jvm 1    | 2015/06/07 10:09:29 | Caused by:
INFO   | jvm 1    | 2015/06/07 10:09:29 | com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure||The last packet successfully received from the server was 84,972 milliseconds ago.  The last packet sent successfully to the server was 1 milliseconds ago.

etc.

The newest eror:
http://pastebin.com/VRkj7fAd

2015-06-07 10:28:00  WARN: Communications link failure

The last packet successfully received from the server was 116,370 milliseconds ago.  The last packet sent successfully to the server was 0 milliseconds ago. - com.mysql.jdbc.exceptions.jdbc4.CommunicationsException (null:-1)

2015-06-07 10:39:14  INFO: device: 1, time: Sun Jun 07 10:37:20 CEST 2015, lat: 52.22578, lon: 18.274043333333335
2015-06-07 10:39:16  WARN: Connections could not be acquired from the underlying database! - java.sql.SQLException (SqlUtils.java:118)
2015-06-07 10:39:16  WARN: Connections could not be acquired from the underlying database! - java.sql.SQLException (SqlUtils.java:118)
...
2015-06-07 10:38:52  WARN: Connections could not be acquired from the underlying database! - java.sql.SQLException (SqlUtils.java:118)
2015-06-07 10:38:52  WARN: An SQLException was provoked by the following failure: com.mchange.v2.resourcepool.ResourcePoolException: A ResourcePool cannot acquire a new resource -- the factory or source appears to be down. - java.sql.SQLException (SqlUtils.java:118)

It looks like your are using non-standard web interface.

Yes, you are right. I'm using http://traccar.litvak.su/. I will repost on their support.

I have had this issue myself a few times
every time it been that i added some app and is used a port that Traccar tried to start listening and i see in your conf for have all protocols enabled disable all the ones you dont use (you should do this as good practices anyhow)

BTW i am no Traccar expert, just a keen user, who learn a bit