Time Machine: “An error occurred while…: Apple Support Communities

Linc Davis has figured it out. Makes sense with the suggestion he gives and the poster said it worked.

Connect the drive directly to a USB port on the MBP.

In the Energy Saver preference pane, uncheck “Put hard disks to sleep…” if checked.

If neither of the above helps, boot in safe mode and try again.

via Time Machine: “An error occurred while…: Apple Support Communities.