I don't know how to reproduce this issue...
I created a bot like StrangerBot and when there are around 14-16 users connected (about 20 minutes after starting the bot) the bot starts to fail with the updates.
The bot should take the ID of the user and put it in a variable
The bot can't take the ID and the variable remains empty.
Operating System: Windows Server 2012 R2
Version of Python, python-telegram-bot & dependencies:
python -m telegram
python-telegram-bot 5.0.0
urllib3 1.17
certifi 2016.08.31
future 0.15.2
Python 3.5.2 (v3.5.2:4def2a2901a5, Jun 25 2016, 22:18:55) [MSC v.1900 64 bit (AMD64)]
It just give a general error about "the update".
I attached an image.

Hello!
What you are seeing is the default log entry that shows when your code raises a TelegramError. That means that one of your API calls failed.
To get more details on the error, you can register an error handler (for general handling of errors, eg logging them) or wrap your API calls in a try/except block (to handle a specific API call).
Read this wiki article: https://github.com/python-telegram-bot/python-telegram-bot/wiki/Exception-Handling
I discovered the error
It was because the user blocked the bot and the code didn't continue
This problem might have been caused by misformatted messages on my machine
Most helpful comment
I discovered the error
It was because the user blocked the bot and the code didn't continue