Error-10000: could not unmount disk is an annoying message which may appear while using disk utility in order to unmount partition. This error restricts to unmount your Mac volume. But the good news is that it is possible to overcome from error-10000: could not unmount disk. Generally this error appears when the file in some partition is being used. In this condition you will have to relaunch the finder through control+option+clicking at finder icon in Dock then selecting the relaunch option. Unmount partition through choosing it in disk utility and clicking at the unmount from the tool-bar. Thus you can fix error-10000: could not unmount disk. However this steps require technical expertise and any mistake during performing these measures could leads to deletion of other important stored file too. The situation becomes more troublesome if there is no updated copy of lost file, but no need to panic at all! Because here comes the Mac data recovery for restoring the lost file, regardless of data loss situations. This is the widely used third party application to recover data from every type of Mac volume effectively. So by opting this tool you do not have to worry any more about inaccessibility of precious file.