telegram.ext.dispatcher - ERROR - No error handlers are registered, logging exception. Traceback (most recent call last)

Hi, I just install the Telegram Bot on my Debian 10 VPS with Python 3.9.4 but I get this error:

2021-04-26 23:55:14,370 - telegram.ext.dispatcher - ERROR - No error handlers are registered, logging exception.
Traceback (most recent call last):
 File "/home/me/environments/binance39/lib/python3.9/site-packages/telegram/ext/dispatcher.py", line 442, in process_update
   handler.handle_update(update, self, check, context)
 File "/home/me/environments/binance39/lib/python3.9/site-packages/telegram/ext/conversationhandler.py", line 549, in handle_update
   new_state = handler.handle_update(update, dispatcher, check_result, context)
 File "/home/me/environments/binance39/lib/python3.9/site-packages/telegram/ext/handler.py", line 160, in handle_update
   return self.callback(update, context)
 File "/home/me/BTB-manager-telegram/btb_manager_telegram/handlers.py", line 251, in start
   update.message.reply_text(
 File "/home/me/environments/binance39/lib/python3.9/site-packages/telegram/message.py", line 689, in reply_text
   return self.bot.send_message(
 File "/home/me/environments/binance39/lib/python3.9/site-packages/telegram/bot.py", line 127, in decorator
   result = func(*args, **kwargs)
 File "/home/me/environments/binance39/lib/python3.9/site-packages/telegram/bot.py", line 475, in send_message
   return self._message(  # type: ignore[return-value]
 File "/home/me/environments/binance39/lib/python3.9/site-packages/telegram/bot.py", line 296, in _message
   result = self._post(endpoint, data, timeout=timeout, api_kwargs=api_kwargs)
 File "/home/me/environments/binance39/lib/python3.9/site-packages/telegram/bot.py", line 259, in _post
   return self.request.post(
 File "/home/me/environments/binance39/lib/python3.9/site-packages/telegram/utils/request.py", line 349, in post
   result = self._request_wrapper(
 File "/home/me/environments/binance39/lib/python3.9/site-packages/telegram/utils/request.py", line 272, in _request_wrapper
   raise BadRequest(message)
telegram.error.BadRequest: Can't parse entities: can't find end of bold entity at byte offset 9

I have also tried with Python 3.7 (which is the default in Debian 10) without chance. What I do wrong? Thanks for any advice. Dav