«unable to expand». what error 79 and error 1 are telling you.

what error 79, error 1 and error 2 mean

Archive Utility does not invent its numbers. they come straight from the system's error table, the same one every command on your Mac uses, and each has a one-line meaning:

• error 79, «inappropriate file type or format»: the contents are not a zip the tool can read: an HTML page saved under a .zip name, a download that stopped early, or an archive written in a way Apple's unpacker does not accept.
• error 1, «operation not permitted»: the archive was read fine; writing the result was refused. a locked or read-only destination, or a file inside the archive that macOS will not create where it was asked to.
• error 2, «no such file or directory»: a path is missing, usually the archive itself moved or was renamed while Finder still pointed at the old name, or a folder it wanted to write into is gone.

the table itself is public; the three lines are in the kernel's errno header: sys/errno.h in Apple's xnu source

the reverse case — a zip your Mac made that confuses everybody else — is the folder called __MACOSX inside it: what the __MACOSX folder in a zip is

error 79 is almost never about a broken zip

the guides ranking for this say «corrupted» and tell you to redownload. sometimes that is right. more often the file was never an archive: a login page or a «file expired» notice, downloaded through a link that promised a zip, lands on your disk as a .zip that is really text. Archive Utility looks inside, finds no zip signature, and says so.

on macOS 26 the dialog for a file that is not an archive does not even show the number: it says «unable to expand “file.zip”. it is in an unsupported format». older systems spelled it out as «(Error 79 - Inappropriate file type or format.)», which is why that string is what people search for.

one command tells you what you are holding

1. open Terminal. it is in Applications → Utilities, or type its name in Spotlight.
2. type `file ` with a trailing space, then drag the archive from Finder onto the Terminal window: the full path is filled in.
3. press return. «Zip archive data» means a real zip — go to the next section. «HTML document» or «ASCII text» means there is nothing to unpack; the download has to be redone from a page where you are actually signed in. «RAR archive data» or «7-zip archive data» means the extension is lying about the format.

if it says rar, Finder has no handler for that format at all, and the answer is a different page: open a rar file on a Mac

a 7z renamed to .zip is not the problem either: on macOS 26 Archive Utility reads the contents, not the name, and opens it on a double-click as if nothing were wrong. if you were told error 79 «is a 7z pretending to be a zip», that is not what you are looking at.

unzip it from Terminal: ditto, unzip and tar

Archive Utility is one of four unpackers on your Mac, and the strictest. the other three are commands, ship with every macOS, and a zip Finder refuses very often opens with one of them — that is the pattern in the Apple Community threads: the same file fails on a double-click and unpacks cleanly from the command line.

one such thread, with the archive verified intact by `unzip -t` and still refused by Finder on two macOS versions: Finder, opening some ZIP archives, makes error 79 — Apple Community

ditto: the closest thing to Archive Utility

1. in Terminal, `cd` into the folder that holds the archive, or type `cd ` and drag the folder onto the window.
2. run `ditto -x -k archive.zip unpacked`. `-x` extracts, `-k` says the input is a zip; `unpacked` is a new folder the contents go into.
3. if it prints «Couldn't read PKZip signature», the file is not a zip — that is the HTML-page case from the section above, not a ditto problem.

ditto is Apple's own tool, shipped with every macOS since the first one; `man ditto` on your Mac lists the flags, and the same page is mirrored here: ditto — macOS manual page

unzip and tar, when ditto also says no

`unzip -t archive.zip` tests the archive without writing anything and says either «No errors detected» or what is wrong — the fastest way to tell a truncated download from a picky unpacker. `unzip archive.zip -d unpacked` then extracts it; the classic Info-ZIP tool tolerates more oddly built zips than Finder does.

`tar -xf archive.zip` is the third route. macOS's tar is bsdtar and reads zip, 7z, rar, gz and the rest by looking at the contents — the name is ignored. if a file was a 7z all along, this is the command that opens it without you renaming anything.

error 1: where the file is being written, not what it is

a read-only folder does not produce error 1 any more: on macOS 26.6.2 Archive Utility notices and quietly unpacks into Downloads instead. what still stops it: a zip made elsewhere with a path inside that macOS refuses to create, or a disk out of space. in Terminal the same failure names the exact file it choked on, which the Finder dialog never does.

an iCloud Photos download is the case people meet most. the zip is fine; the photos inside are heic, and the thing you cannot open afterwards is not the archive.

that one has its own two-minute answer: convert heic to jpg on a Mac

the short version: if `file` says zip, one of the three commands opens it, and `ditto` first. the price of this route is knowing which command to type and what its refusal means — not the result, which is the same folder Finder would have made.

how hop opens an archive that Archive Utility refused

hop does not repair a file. a download that is really an HTML page, or a zip cut off halfway, is not an archive, and hop will not open it any more than the four tools above will. that covers most «error 79» you meet; this section is for the other cases.

hop's archives module opens a window you drop things into — or paste with ⌘V, several at once. what you add waits in a list until you press the button, and archives are unpacked to the Desktop, next to the original, or into a folder you pick. zip, rar, 7z, tar, tar.gz, tar.bz2, tar.xz and gz are covered; rar and 7z fetch a small signature-verified helper (~6 mb) the first time one turns up.

what this changes and what it does not

the difference is not that hop reads something your Mac cannot; the commands above read the same formats. the difference is that you do not have to know which of three commands applies or what «Couldn't read PKZip signature» means, and that an archive from a colleague unpacks where you are looking instead of in a Terminal window. for one zip a week that is a small thing; for a job that hands you archives daily it is the reason to have the module at all.

hop's default-app setting offers to take rar only when no Apple app owns it — zip, 7z and the rest stay with Archive Utility.

the module in full — what it packs, where results land, and how the Finder default is handled: archives on the features page

when it still says unable to expand

the zip opens on Windows but not on the Mac

that is the Apple Community case: an archive written by a web service in a way Finder's unpacker rejects and everything else accepts. `unzip` or `ditto` opens it; there is no setting that makes Finder more forgiving.

«error 2 - no such file or directory»

• the archive was renamed or moved while the unpack was starting, and Finder held the old path. run it again from where the file is now.
• the download is still in progress. a browser shows the final name before the last bytes arrive; wait for the progress to finish, then double-click.
• the file is a cloud placeholder — a Desktop & Documents item not yet downloaded from iCloud. the cloud icon next to the name is the tell; click it to fetch the file first.
• the size is wrong. compare it with what the page promised: a truncated download usually fails on the last file, not the first, and `unzip -t` confirms it in a second.

a third-party unarchiver you installed years ago has the file

if the dialog belongs to some other app, that app owns the .zip type. right-click the archive → Open With → Archive Utility to test the built-in one, or remove the old app properly so the type returns to Apple.

properly means with its preferences and helper files, not just the icon: uninstall an app with its leftovers

and if it refuses to go at all, that is a separate problem with its own causes: an app that will not delete

Apple's own page covers the working case only, zip and unzip in Finder, and stops before any of the errors above: zip and unzip files and folders on Mac — Apple Support

frequently asked questions

what does error 79 mean on a Mac?

«inappropriate file type or format» — the system's wording for errno 79. Archive Utility looked inside and did not find an archive it can read. most often the file is not a zip at all: an error page saved under a .zip name, or a download that stopped early.

why can't i unzip a file on my Mac when it works on Windows?

Finder's unpacker is stricter than most. an archive written in an unusual but valid way can be refused by Archive Utility and accepted by `unzip`, `ditto` and every Windows tool. open it from Terminal; the file is fine.

how do i unzip a file in Terminal on a Mac?

`cd` into the folder, then `ditto -x -k archive.zip out` or `unzip archive.zip -d out`. both are already installed. `tar -xf archive.zip` works too and also reads 7z and rar.

is my zip file corrupted?

`unzip -t archive.zip` tests it without extracting and tells you. «No errors detected» means the archive is intact and the problem is the unpacker; anything else means redownload.

what is Archive Utility error 1 operation not permitted?

the archive was read; writing the result was refused: a path inside it that macOS will not create, or a destination it cannot write to. unpacking from Terminal names the exact file it stopped on.

does hop fix error 79?

no, and nothing does when the file is not an archive. hop opens real archives — zip, rar, 7z, tar and the rest — by drag and drop instead of a command, and unpacks rar on a double-click, which Finder cannot.

the tool behind this

done with file archives

other things people do

• 7z your Mac opens. rar it will not.archives
• a folder of heic, and something that wants jpgfile converter
• forty documents, and Word is not installedfile converter