In response to the latest hacking of iCloud Apple has tightened security. A few days ago they implemented App Specific Passwords If you have third party applications that use iCloud or iCloud Drive they need to be assigned a password.
Recently you may have gotten an email from Apple like this:
They were just warning us that the App Specific Password requirement was going to be activated. Well, I should have paid more attention to that email!! I had forgotten about one or two applications I had on my Mac that used iCloud. As a result I kept getting this error message:
I blocked out my AppleID here. So, I did a bunch of research online about this error. Then I had an epiphany! I recognized that little icon in the window (at first I thought it was the Mavericks Calendar program) as a little menubar calendar app I use sometimes called Fantastical. This is a nice calendar app, but I digress.
About the same time I realized what app was generating this error message, I found an article online about App Specific Passwords directing me to an Apple Support Article on how to set them up. I followed the procedures in the article, obtained a password for Fantastical (you can have 25 passwords total) and then pasted it into the error message like so:
The moral to the story, at least give a cursory glance at emails that you receive from Apple! Even tech guys can breeze through these items to their own dismay, but we all catch on eventually, right :)?