telethon :A wait of 16480 seconds is required (caused by ResolveUsernameRequest)

Question

i'm trying to use telethon to send messages to telegram groups. after some times runing, it reruens: A wait of 16480 seconds is required (caused by ResolveUsernameRequest). the code is:

async def main():
   print(time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(time.time())))
   config = configparser.ConfigParser()
   config.read("seetings.ini",encoding= 'utf-8')
   message = config['Customer']['message']
   internal = config['Customer']['internal']
   count = 0
   excel_data = pandas.read_excel('tg_groups.xlsx', sheet_name='Groups')
   for column in excel_data['GroupUsername'].tolist():
      try:
        if str(excel_data['GroupUsername'][count]) == 'None':
            count += 1
            continue
        else:
            chat = await client.get_input_entity(str(excel_data['GroGroupUsernameupID'][count]))
            await client.send_message(entity=chat, message=message)              
    except Exception as e:
        print(e)
        time.sleep(int(internal))
        count = count + 1
        continue
    time.sleep(int(internal))
    count = count + 1

if __name__ == '__main__':
   
    if proxytype == 'HTTP':
      print('HTTP')
      client = TelegramClient('phone'+phone, api_id, api_hash, proxy=(socks.HTTP, 'localhost',                     int(proxyport))).start()
    if proxytype == 'socks5':
      print('SOCKS5')
      client = TelegramClient('phone'+phone, api_id, api_hash, proxy=(socks.SCOKS5, 'localhost',     int(proxyport))).start()
    myself = client.get_me()
    print(myself)
    freqm = config['Customer']['freq']
    print(int(freqm))
 while True:
    with client:
        client.loop.run_until_complete(main())
    time.sleep(int(freqm))`

`
from the 'Entity' guide, it says get_input_entity method will search the user info from session file cache, why it it still call the 'ResolveUsernameRequest'to get the user info? anything i missed? thanks for any advice.

'Entity' guide, it says get_input_entity method will search the user info from session file cache, why it it still call the 'ResolveUsernameRequest'to get the user info? anything i missed or the session file didn't keep the user info cache?