title: Telethon - Error when retrieve user info
body: <p>I'm stuck with an error in telethon, when trying to get users data.
  First, I get new messages from some groups, it's ok, but when I try to get user data (name, first_name etc) - sometimes it's ok, but mostly fails with error</p>
  
  <pre><code>ValueError: Could not find the input entity for "12345678". 
  Please read https://telethon.readthedocs.io/en/latest/extra/basic/entities.html 
  to find out more details.
  </code></pre>
  
  <p>I read that article a lot of times, tried to use also <strong>client.get_input_entity</strong> as it says, but it doesn't help</p>
  
  <p>Here is my code:</p>
  
  <pre><code>import logging
  from telethon import TelegramClient, events
  
  
  logging.basicConfig(level=logging.WARNING)
  logging.getLogger('asyncio').setLevel(logging.ERROR)
  
  entity = 'session'  # session
  api_id = 123456
  api_hash = 'hash'
  phone = '1234567'
  
  chats = ['group1', 'group2', 'group3']
  
  
  client = TelegramClient(entity, api_id, api_hash)
  
  
  @client.on(events.NewMessage(chats=chats))
  async def normal_handler(event):
  
  
  print(event.message.message)
  print(event.date)
  print(event.from_id)
  print(event.message.to_id)
  #user = await client.get_input_entity(event.from_id)
  user = await client.get_entity(event.from_id)
  
  
  
  client.start()
  client.run_until_disconnected()
  </code></pre>
  
  <p>How can I fix that?</p>
  
  <p>And one more question, how can I retrieve info about group? 
  I know it's id from <strong>event.message.to_id</strong>, but can't get how to get it's name.</p>
  
  <p><a href="https://telethon.readthedocs.io/en/latest/index.html" rel="nofollow noreferrer">The docs for the library</a> looks not very friendly for beginners. =(</p>
  
  <p>Thank you</p>