If you get this error, most likely you need to tune your transaction timeoutS (there are many!)
Look for Oracle Support documents "Recommended Timeout Configuration When Using an External Transaction Processing Monitor and XA with Oracle (Doc ID 338880.1)" and for "WebLogic Server: Getting "XAER_NOTA : The XID is not valid" Exception with XA Datasource (Doc ID 1352715.1)"
The golden rule is "global transaction timeout < session timeout < distributed_lock_timeout", so check the value of the DB "distributed_lock_timeout" value.
See also http://www.javamonamour.org/2011/09/pending-xa-transactions-on-oracle-db.html and http://www.javamonamour.org/2015/10/ora-24756-transaction-does-not-exist.html
Look for Oracle Support documents "Recommended Timeout Configuration When Using an External Transaction Processing Monitor and XA with Oracle (Doc ID 338880.1)" and for "WebLogic Server: Getting "XAER_NOTA : The XID is not valid" Exception with XA Datasource (Doc ID 1352715.1)"
The golden rule is "global transaction timeout < session timeout < distributed_lock_timeout", so check the value of the DB "distributed_lock_timeout" value.
See also http://www.javamonamour.org/2011/09/pending-xa-transactions-on-oracle-db.html and http://www.javamonamour.org/2015/10/ora-24756-transaction-does-not-exist.html