applyEdits fails in ArcGIS JSAPI - arcgis-js-api

Question

I am using a feature layer in JSAPI, where I edit a feature by the standard selection, change attributes, applyEdits process. It seems that there is a bug in JSAPI both 3.12 and 3.14 which makes the apply edits fail on certain features. The callback just errors out without any clue.
The interesting observations:
Failure only happens on certain features and all cases belong to a particular layer (other features in that layer are just fine).
Changing from 3.12 to 3.14 the features that cause the error are changed but did not go away.
Here is a quick snippet of the code:
sq = buildSelectionQuery();
if (sq) {
all(assetsFeatureLayers.map(function (l) { return l.selectFeatures(sq, esri.layers.FeatureLayer.SELECTION_NEW).promise;})
).then(function (fls) {
console.log('sel res', fls);
all(fls.map(function (r, i) {
var fs = r[0]; // the first is an array of selected features
var l = assetsFeatureLayers[i];
console.log(fs);
if (fs.length > 0) {
console.log("Switching phases to: ", tph);
fs.forEach(function (f) {
f.attributes['phasecode'] = tph;
});
console.log("Saving switched phases for layer: ", l.name);
return l.applyEdits(null, fs, null); //.promise;
} else {
return null;
}
})).then(function (l) {
console.log("Phase switching finished successfully!", l);
clearAllSelections();
}, function (e) {
console.log("Error switching phases!", e);
clearAllSelections();
});
});
}

Answer 1

OK, I found the root cause. We are using ESRI's PHP proxy, and it was a bug in that. Upgrading to the latest 1.1 beta solved the issue. Here is the link to their repo: https://github.com/Esri/resource-proxy