spine.log
If you have mysterious errors or your Spine install won't start, check or post the contents of this file.

Windows: <user home folder>\Spine\spine.log
Mac: <user home folder>/Library/Application Support/Spine/spine.log
Linux: <user home folder>/.spine/spine.log

backups
If your file gets corrupted somehow (like if you were unfortunate enough to have lost power in the middle of saving.) or you just accidentally saved over something important, you'll be glad to know that Spine actually saves backups of your projects.

Windows: <user home folder>\Spine\backup\
Mac: <user home folder>/Library/Application Support/Spine/backup/
Linux: <user home folder>/.spine/backup/