I am using a MEANJS stack, I upload an image using ng-flow and save the imgsrc as base64 url.
data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAARkAAACzCAYAAAC94Gg
Recently, I confronted with this issue and I just added app.use(bodyParser.json({ limit: "50mb" })); this one line in my express app, it just worked :)
And also one more thing don't forget to add above code line before app.use(bodyParser.json()) this otherwise, it won't work.
Whatever you set values regarding bodyparser you've to do before the above code line.
Because, express will go back to its default values and your change won't get effect. I hope this might help :)