Bench update error (v4 to v5)

I am trying to migrate v4 to v5

but bench update gives this error
No module named num2words

Also, when I do, bench update --requirements it does nothing.

How to update requirement manually?

Need to update email_reply_parser and num2words requirement?

Solved after updating Ubuntu Server.
But still any answer to update manually requirements is very useful?

Thanks,
Sambhaji