Keywords: Signals Notebook, Change email address, error, request arguments.
Details: You are trying to change the email address of a user, and you get the error - "One or more request arguments are missing or invalid, Please contact your administrator."
Solution:
To fix this error, you need to go to the System Configuration under System Settings > API Key, and delete the API Key associated to the email address you are trying to rename.
Go back to the Users, and change the email address. Save the changes. Go back to the API Key, create a new one with the new user email address, and configure your API if is necessary with the new key.