[UWP] Error while www loading

Hello
some time I get the error "You are trying to load data from a www stream which has not completed the download yet. You need to yield the download or wait until isDone returns true." as if I wouldn't yield it.

At the moment I just try to avoid this problem by waiting a little longer until the asset bundle is loaded.

Reproducable on Unity 5.4.2f2 and 5.4.4f1 (5.5.1f1 there are other problems)

Code (CSharp):

1.  
2. using (WWW www = new WWW(path)) {
3. #if UNITY_UWP
4.             Debug.Log("try to load www path " + path);
5. #endif
6.             yield return www;
7. #if UNITY_UWP
8.             Debug.Log("after yield www.isDone " + www.isDone + ", www.progress " + www.progress+ ", www.error '" + www.error + "' , assetBundle =" +
9. (www.assetBundle == null ? "null" : www.assetBundle.ToString()));
10.             // Strange error on Windows Store App:
11.             // You are trying to load data from a www stream which has not completed the download yet.
12.             // You need to yield the download or wait until isDone returns true.
13.             float waitTime = 0f;
14.             while (!www.isDone || www.progress < 1f || www.assetBundle == null)
15.             {
16.                 yield return new WaitForSeconds(0.1f);
17.                 waitTime += 0.1f;
18.                 Debug.Log("www.isDone " + www.isDone + ", www.progress " + www.progress + ", assetBundle =" + (www.assetBundle == null ? "null" : www.assetBundle.ToString()));
19.                 if(waitTime > 5f)
20.                 {
21.                     Debug.Log("ERROR AssetBundle couldn't be loaded!");
22.                     yield break;
23.                 }
24.             }
25. #endif
26.  
27.             if (!string.IsNullOrEmpty(www.error)) {
28.                 Debug.LogWarning(www.error);
29.                 yield break;
30.             }
31.  
32.             ...
33.         }

 

atm Unity 5.4.4f1