NullReferenceException in StartCoroutine method

by JamesB   Last Updated November 25, 2016 08:05 AM

Maybe it's a repeated subject in the community but other answers didn't solved my question...

I tried as the tutorial: and worked fine in start method but when I try:

public Class A
 //    ...CODE...
 new B().JSONRequest(jsonString);

public Class B

public void JSONRequest(string json) { 
string url = URL.LOCAL.url;
Hashtable postHeader = new Hashtable();
postHeader.Add("Content-Type", "application/json"); 
UTF8Encoding encoding = new System.Text.UTF8Encoding(); 
WWW request = new WWW(url, encoding.GetBytes(requisicaoJSON.ToCharArray()), HashtableToDictionary<string, string>(postHeader));
 print("Request: "+request); 


IEnumerator WaitForRequest(WWW www)
    yield return www;
        // check for errors
        if (www.error == null)
            Debug.Log("WWW Ok!: " +;
        } else {
            Debug.Log("WWW Error: "+ www.error);

It gives me in the StartRoutine line: NullReferenceException UnityEngine.MonoBehaviour.StartCoroutine (IEnumerator routine) (at C:/buildslave/unity/build/artifacts/generated/common/runtime/UnityEngineMonoBehaviourBindings.gen.cs:61

Console prints Request: UnityEngine.WWW so it does not appear to be null. –

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