Time machine error -1 is the clear indication of problem associated with this backing up application. By the way Time machine is one of the widely used built in tool that is used by various users worldwide. Unfortunately due to unforeseen reasons there might be inconvenience come across while using this application. There is one issue reported by several Mac users is time machine error -1. This type of error basically appears when there is issue associated with time machine volume due to file system damaged. The bad news is that your earlier backup would seem invisible and you prevented to create further backup. Most of us become frustrated in such condition and wander in searching proper way to resolve resolve time machine error -1. But do not bother you can overcome from this problem. In order to do this disk diagnostic program like disk utility can be used for repairing permission of drive. Alternatively you can even use fsck in single user mode. But if time machine error -1 still appears, reformatting the hard drive is the mere option. After that reinstall this application and in case any sort of data loss here comes Mac Data Recovery Software. It is the best and proficient tool for Mac data recovery.