Are you experiencing mac error startup? Then you must take immediate course of action else the situation would be out of control. No doubt Mac systems are very reliable but sometimes it gets cranky and show weird behavior. One such abnormal behavior when Mac does not boot or show mac error startup. Well there could be problem related with power supply, logic board, OS failure, hard drive and user account issue etc. As you can't access your system completely when it failed to start. So you must take resolving this issue into account and to fix mac error startup you can take feasible measures which include making sure that power supply is fine and remove the unnecessary application. Alternatively you can check the disk permission and repair it through disk utility. However if you failed to resolve the issue even after using these measure. Then you need to reformat hard drive to fix mac error startup. Consequently all the data stored in hard drive has removed after format and here you look into recovery which can be achieved through drive backup. Otherwise opt third party Mac Data Recovery Software. This is handy way for restoring lost or formatted data completely.