I had the same problem, I think in Chart.js 2.x.x the approach is slightly different like below.
ticks: {
callback: function(label, index, labels) {
return label/1000+'k';
}
}
More in details
var options = {
scales: {
yAxes: [
{
ticks: {
callback: function(label, index, labels) {
return label/1000+'k';
}
},
scaleLabel: {
display: true,
labelString: '1k = 1000'
}
}
]
}
}