File Creation and Modification Dates
About Inconsistent File Dates
The rules macOS enforces between file creation and modification dates, how the Automatically correct inconsistent dates option resolves conflicts, and what works for dates before 1970.
macOS enforces a number of “common sense” restrictions on your use of creation and modification dates for files:
- a file cannot have been modified before it was created
- a file cannot have been created after it was modified
- a file cannot have been created or modified at a future date
This means that if your file was created yesterday, it cannot possibly have been modified last week (it didn’t exist yet) and if your file is on the hard disk this means it already exists and can thus not be first created tomorrow.
The way in which different versions of macOS enforce these common sense restrictions, however, has changed a few times in the last few years and has lead to some “strange” behavior when you are manually changing these dates with a tool such as File Multi Tool.
When the “Automatically correct inconsistent dates” checkbox is ticked, File Multi Tool will automatically deal with these problems by doing the common sense thing:
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If the new creation date of the file is later than the last modification date of the file (i.e. it would now have been created after it was last modified, which makes no sense), File Multi Tool will put the modification date to the new creation date, (i.e. the file will have been created and modified at the same moment, which makes sense).
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As a user of these features you need to be aware of the fact that changing one of the two dates (modification or creation date) may also result in a change in the other.
We recommend leaving this feature switched on, but if the checkbox is unticked, the program will ask you to make a choice for each inconsistent file date problem individually.
Dates before 1970
On APFS volumes, the default since macOS 10.13, file creation and modification dates between the 21st of September 1677 and the 11th of April 2262 can be set and are shown correctly by the Finder. Older file systems and some network volumes still refuse dates before the early 1970s.
One quirk remains: when a file already has a creation date before 1970 and its modification date is then set to a date after 1970, macOS silently moves the creation date forward to match. If a historic creation date jumps forward, set the modification date first and the creation date second.