"Error 401 - Cannot authenticate over ajax calls" on iOS

Hi, I'm writing an app (using Ionic 2) that uploads pictures to my ownCloud server via Webdav. Here is the relevant part of my code:

upload(imgToUpload) {
  let transfer = new Transfer();
  let URL: "https://username:password@owncloud.../remote.php/webdav/folder/"
  let options = {
    httpMethod: "PUT"

  transfer.upload(imgToUpload, URL, options, true).then(
    (succ) => {},
    (err) => {console.log(err.http_status+" "+err.body);}

I'm using the Ionic File Transfer Plugin which internally uses a PUT request. The whole thing works on Android, but on iOS I get the following error:

401 <?xml version="1.0" encoding="utf-8"?> 
  <d:error xmlns:d="DAV:" xmlns:s="http://sabredav.org/ns">
    <s:message>Cannot authenticate over ajax calls</s:message>

I'm using basic authentication. I looked through the ownCloud source code and it seems that the error originates here but I don't see why it's thrown or why this only happens on iOS.

Can anyone help me get this sorted out?
Thanks in advance!

If it works from Android but not from IOS then i guess that framework is doing something different between both platforms.

Have you considered asking at e.g. https://forum.ionicframework.com ? They might be able to explain you the differences here.

Thanks, I'll try that