Could not find new XAResource to use for recovering non-serializable XAResource
This is a warning by the JBoss transaction manager that the server previous crashed (or was stopped brutally) while some transactions were active.
Some transaction data is still available on disk and could in theory be used by the transaction manager to restart the transaction after the server has restarted, but this functionality is not implemented by Nuxeo (and not implemented by most vendors either).
To get rid of the stale transaction data, while Nuxeo is stopped you should remove the folder
$nuxeo.data.dir/tx-object-store/ if nuxeo.data.dir is defined in your nuxeo.conf).