New URI Malformed error in most Apps

Starting from hours ago today, I noticed most Shiny Apps on broke on Chromium-based browsers (e.g., Chrome and Edge) with the following error:

The same error messages occur in almost all other Apps I visited. However, Safari is unaffected.

I already posted this issue on GitHub at rstudio/rsconnect/issues/537 as the issue occurred once already about three weeks ago and disappeared without any clue. But the problem returned just hours ago.

By inspecting the sources using Chrome's DevTools, the issue seem to be in __assets__/lib/transport/receiver/eventsource.js :

'use strict';

var inherits = require('inherits')
  , EventEmitter = require('events').EventEmitter
  , EventSourceDriver = require('eventsource')

var debug = function() {};
if ("production" !== 'production') {
  debug = require('debug')('sockjs-client:receiver:eventsource');

function EventSourceReceiver(url) {

  var self = this;
  var es = = new EventSourceDriver(url);
  es.onmessage = function(e) {
    self.emit('message', decodeURI(;
  es.onerror = function(e) {
    debug('error', es.readyState, e);
    // ES on reconnection has readyState = 0 or 1.
    // on network error it's CLOSED = 2
    var reason = (es.readyState !== 2 ? 'network' : 'permanent');

inherits(EventSourceReceiver, EventEmitter);

EventSourceReceiver.prototype.abort = function() {

EventSourceReceiver.prototype._cleanup = function() {
  var es =;
  if (es) {
    es.onmessage = es.onerror = null;
    es.close(); = null;

EventSourceReceiver.prototype._close = function(reason) {
  debug('close', reason);
  var self = this;
  // Safari and chrome < 15 crash if we close window before
  // waiting for ES cleanup. See:
  // link manually removed because of new user posting restriction
  setTimeout(function() {
    self.emit('close', null, reason);
  }, 200);

module.exports = EventSourceReceiver;

The error seemed to be on line 21:

self.emit('message', decodeURI(;

Could you please confirm if this issue is related to shinyapps or possibly another third party?

Thank you in advance.

Repeating some information from

We have identified a problem handling some messages sent from the Shiny/R server to the browser. In particular, messages containing the % character might incorrectly cause an error reported by decodeURI.

This problem is not seen by everyone, but if folks have very particular browser/network combinations, they will see this error across a number of applications.

We have reverted the source of this problem, but running applications may need to be restarted.