Pairaphrase uses multi-factor authentication to keep it's users safe. This requires a user to request and enter a verification code sent to an email address, to a smartphone via sms or to an authentication application.
If you enter the code incorrectly, you will receive an invalid code message. This means that you did not enter the code correctly. Simply retype the code correctly to login.
Verification codes are time sensitive. If you don't enter them immediately they typically expire and you will receive either an invalid code message or a verification code has expired message. You have to request a new code when your code times out. If you are using a 2FA authentication application like Google Authenticator or Authy you can wait for the application to generate a new code.