KB-1206 "Communications link failure during rollback(). Transaction resolution unknown" error thrown in application server log


The following error is displayed in application server log:

INFO  [stdout] (ajp-/ 2016-07-06 13:16:52,016 [ajp-/] ERROR org.hibernate.util.JDBCExceptionReporter - Statement cancelled due to timeout or client request
WARN  [com.arjuna.ats.jta] (ajp-/ ARJUNA016045: attempted rollback of < formatId=131077, gtrid_length=29, bqual_length=36, tx_uid=0:ffffac176096:b16e:5776f2fb:4971, node_name=1, branch_uid=0:ffffac176096:b16e:5776f2fb:4975, subordinatenodename=null, eis_name=0 > (org.apache.commons.dbcp2.managed.LocalXAConnectionFactory$LocalXAResource@420114fe) failed with exception code ARJUNA016099: Unknown error code:0: javax.transaction.xa.XAException
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Communications link failure during rollback(). Transaction resolution unknown.


One of the possible causes is the mismatch of the maximum transmission unit (MTU) between the client and server.


If using Linux, to determine the MTU value, run the following command:


This will display the network interface configurations of the server hosting the database instance, along with the MTU value.

If the Appian instance and database are hosted on the same network, review the MTU settings with your network administrator including any firewalls, proxys, or any other entity regulating the traffic between the servers.

If the Appian instance is hosted on Appian Cloud and the database is being accessed over VPN, please contact Appian Support to assist with the MTU troubleshooting.

Affected Versions

This article applies to all versions of Appian.

Last Reviewed: October 2018