title: why web3.eth.getBlock gives null answer and getTransactionReceipt gives error?
body: <p>I am using Web3.py in my python code. The code is like this  </p>
  
  <pre><code>from web3 import Web3   
  w3 = Web3(Web3.HTTPProvider("https://ropsten.infura.io/"))*  
  for i in range(5000000,5100000):  
      print(i)  
      transactionArray = []  
      blockResult = w3.eth.getBlock(i)  
      for tx in blockResult["transactions"]:  
          txResult = binascii.hexlify(tx).decode()  
          print(txResult)
          transactionResult = w3.getTransactionReceipt(txResult)
          print(transactionResult)
  </code></pre>
  
  <p>When I execute this code, getting error</p>
  
  <pre><code>5000000  
  Traceback (most recent call last):
    File "Test06.py", line 27, in &lt;module&gt;
      for tx in blockResult["transactions"]:
  TypeError: 'NoneType' object is not subscriptable
  </code></pre>
  
  <p>but If I start range from 4571699 it gives me the result. Can somebody tell me why I'm getting an error for range starts from 5000000</p>
  
  <p>I use the MAIN NET, so resolved this problem. But now I am getting an error as  </p>
  
  <pre><code>Traceback (most recent call last):   
    File "Test06.py", line 35, in &lt;module&gt;
       transactionResult = w3.getTransactionReceipt(txResult)
  AttributeError: 'Web3' object has no attribute 'getTransactionReceipt'.
  </code></pre>