Every now and then it happens that Mac system stops responding suddenly due to Mac runtime error. It is one of the most critical issue mainly caused due to corruption in system files there are various reasonable factors which can be responsible for occurrence of this very error such as register error, incomplete installation, virus attack, and many more. However in order to fix Mac runtime error you can take the help of disk utility. It is an built in feature which enables the users to troubleshoot any kind of common corruption issue. But in case if the problem still exist even after using disk utility as well then in such situation you can use FSCK command. Run the FSCK command on terminal in single user mode it may fix Mac Runtime error completely. But in case if it also fails to resolve the issue then there is no other option left but to reinstall the Operating system. It will efficiently fix the issue from your Mac system for sure but meanwhile it will also cause removal of all existing files from hard drive. But there no need to worry about that as Mac Data Recovery Software is available now, it can easily recover and restore all your lost or formatted files on Mac. It can even recover files which get lost due to Mac runtime error.