O365 Addin development: Error 457
If you are using an Microsoft Office 365 Developer subscription to develop Addins and see an error 457 when deploying from Visual Studio - chances are you're password has expired and needs changing. The default policy is that the password should change every 90 days.
The simple fix is to fire up a browser and login to the O365 portal where you'll be prompted to change your password. Once you've done this, you'll be able to deploy from Visual Studio again.
If you want to change the default policy, login to the Office 365 Admin - select Service Settings - Passwords and change the "Days before passwords expire:" option.