SFTP session closed undefined

[riklamme]

Session closed (undefined) error with large file sizes (225kb).
Someone an idea

Grunt task is:

'sftp-deploy': {
pages: {
auth: {
host: 'host',
port: 22,
authKey: 'privateKey'
},
cache: false, // 'sftpCache.json',
src: '<%= dir.dist %>',
dest: 'path/on/server', // this is on the remote host
exclusions: [
'<%= dir.dist %>/**/.DS_Store'],
concurrency: 1,
serverSep: '/',
progress: true
}
}, // end sftp-deploy

and i use the --verbose option