Currently this error code is the only result:

Uncaught Error: Unimplemented type: 4
    at Pbf.skip (index.js:191)
    at Pbf.readFields (index.js:41)
    at MVT.readFeatures (MVT.js:250)
    at VectorTile.<anonymous> (featureloader.js:86)


import Map from 'ol/Map.js';
import View from 'ol/View.js';
import MVT from 'ol/format/MVT.js';
import VectorTileLayer from 'ol/layer/VectorTile.js';
import VectorTileSource from 'ol/source/VectorTile.js';

const vectorLayer = new VectorTileLayer({
  source: new VectorTileSource({
    format: new MVT(),
    tilePixelRatio: 1,
    url: 'http://localhost:8080/geoserver/gwc/service/tms/1.0.0/opengeo%3Acountries@EPSG%3A4326@pbf'

new Map({
  layers: [vectorLayer],
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 2
  • 1
    You changed the question and related code without any explanation of transition from old question to the new. How do you expect anybody to notice and understand the change? How can anybody now understand the existing answer to the old question?
    – TomazicM
    Aug 29, 2019 at 13:19
  • That's a message from,the mapbox pbf interpreter which is used by OpenLayers MVT format. github.com/mapbox/pbf/blob/master/index.js Most likely a problem with your server github.com/openlayers/ol-cesium/issues/…
    – Mike
    Aug 29, 2019 at 14:18
  • In this case it may be the server is giving incorrect output because the url is wrong - I would expect to see {z}{x}{z} placeholders so OpenLayers can request the correct tiles
    – Mike
    Aug 29, 2019 at 14:42

1 Answer 1


5.3.3 is a patch release so the assert link doesn't work, but you can get the message via version 5.3.0 https://openlayers.org/en/v5.3.0/doc/errors/#43

layers: vectorLayer,

should be

layers: [vectorLayer],

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