Being a Mac user if you want to know about the error message “Mac file in use cannot copy” then you exactly came to right post. This post will teach you complete information about this error message and what are the required step need to do in this situation. Generally this happen when you are trying to copy the files when it is in use. In your Mac computer if any file is opened and running and in between you copy that file then you will get this error message Mac file in use cannot copy. It is advised you to terminate or close the file and then start copying because until the file remains in running condition doesn't let you copy. When you notice that the Mac file in use cannot copy then do not take it in a light way as it may cause the loss of your important data. As the data is a very essential resource so we need to keep it safely. Loss of data is very unhappy moment for the user. If data backup is available then it can be recovered easily but if this not be case then it is recommended you to use Mac data recovery software.