Finder, opening some ZIP archives, makes error 79, but unzip command line works OK, says ZIP file is good

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rj_oregon Author

Level 1

51 points

Finder, opening some ZIP archives, makes error 79, but unzip command line works OK, says ZIP file is good

Applicable to:

Finder in Monterey 12.6 on Mac Mini;

Finder in Catalina 10.15.7 on MacBook Pro;

FILES utility in iOS 15.7 on iPhone 13mini

Usually I can open ZIP files on several systems running Catalina and Monterey.

But a particular set of ZIPs from an external source (web service, platform called Avii), and they never open / unpack using Finder. When I double-click on Download.zip with Finder, I get

"Archive Utility: unable to expand "Download.zip" into "Downloads".

(Error 79 - Inappropriate file type of format.)"

If I move the file Download.zip to, say, the Desktop, I get the same thing. This is on Mac mini, Monterey 12.6. I get the exact same thing happening on a MacBook Pro running Catalina 10.15.7

So far, I have only seen this with ZIP archives that I download from my business service provider running the Avii service. Zip files from other sources, I seem to have no trouble opening, and no problems generating ZIPs and sending to others.

Before you say, call your service provider Avii, let me point out: I can unpack this same zip file using command line.

cd ~/Downloads

unzip -d foo Download.zip

manages to create directory foo and unpack the zip into that directory. And this works too:

unzip Download.zip

So that is my work-around. I'll let Avii know, but I don't expect more than, hey, try this third-party unarchive utility. And, I try downloading this zip archive multiple times. It is not a one-off glitch.

And, I pushed the file out to iCloud, tried using my phone (iOS 15.7) to open it. Nope.

"The operation couldn't be completed. Inappropriate file type or format. OK?" So, common root problem across iOS and Mac OS, on a valid archive file.

In the past, I have asked my service provider to just send me the files, and they use some other process to generate a zip archive and email that to me. That's not a sustainable solution either. Now that I know I can use command-line, I'll just do that.

The manual page for unzip is long, but I tried a few things. Test archive files:

unzip -t Download.zip

shows the filenames, dates, and says

"No errors detected in compressed data of Download.zip"

Then verbose, list diagnostic info:

unzip -v Download.zip

Archive: Download.zip

Length Method Size Cmpr Date Time CRC-32 Name

-------- ------ ------- ---- ---------- ----- -------- ----

63643 Defl:N 60302 5% 09-28-2022 14:23 57b42a74 ****redaction1****.pdf

48148 Defl:N 37997 21% 09-28-2022 14:23 9f7e2092 ****redaction2****.pdf

48384 Defl:N 45196 7% 09-28-2022 14:23 8534b7dd ****redaction3****.pdf

101611 Defl:N 98081 4% 09-28-2022 14:23 4441cc02 ****redaction4****.pdf

-------- ------- --- -------

261786 241576 8% 4 files

The original (non-redacted) filenames do contain spaces, FYI.

I'm not seeing anything in unzip commend-line options that can tell me about the originator system, file conventions, etc. But unzip is telling me the original is a perfectly good archive, so why is Finder throwing up 79 on it? I cannot provide a zip archive for inspection as it contains payroll information.

*** OK, so what is it about the Mac OS "Archive Utility" embedded within Finder, across Catalina and Monterey, that makes it unable to make a directory and unzip the contents into it? Doesn't Finder just outsource its unZIPping to the command-line unzip (OK, maybe that's a native thought)?

Can someone say what Error Code 79 is telling us?

Also, I tried renaming the zip archive file from Download.zip to foofoo.zip. Opening in Finder causes same error code.

The user forums have some assorted odd stuff in 2-year-old posts, i.e. about rebooting in safe mode, and trying third-party utilities, etc. that I have no interest in trying. Some change broke unzip in Finder, seems like it should be simple to fix at Apple, and it's been years.

MacBook Pro 13″, macOS 10.15

Posted on Oct 1, 2022 8:52 AM

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Answer 1

Oct 1, 2022 7:32 PM in response to rj_oregon

I don't know what the Finder uses to extract .zip files, nor what the error code means. I hate the macOS error codes -- what is the purpose of a code if there is no way to look it up. Apple so loves their secrets.

I encountered a similar issue when I uploaded an archive to a Microsoft SharePoint. When the archive was downloaded, it could not always be opened even when I downloaded to the same computer I used to upload it. I only ever used macOS to do this and never had time to test while uploading & downloading the archive using another OS to confirm. It just may be something in the way these files are handled with their respective service. I know at one time many years ago, that some browsers would modify files being downloaded to a computer. So not completely unheard of.

Maybe you can make a simple script where you can just drag & drop the archive onto it in order to extract the .zip archive using the command line utility which works.

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Answer 2

rj_oregon Author

Level 1

51 points

Oct 2, 2022 7:53 AM in response to rj_oregon

More.

Second thing I tried, just to test out zip archives on iOS, I found a little zip archive from another source, put it on iCloud, used FILES to open it in iOS, and it works, sort of, on my phone, so with a "good" archive I was able to preview the content. But my problematic Avii zip archives get the bad file warning from iOS. [Speculation, common code base between iOS and Mac OS for Archive Utility or its merged equivalent?]

Third thing I tried, I searched my Apps on Mac OS and found the Archive Utility app (v. 10.15, on Monterey 12.6, Mac mini). Started it, tried File -> Expand Archive -> Download.zip, failed with same error code.

Played in Archive Utility -> Preferences -> Use Archive Format, but all the selections there, no change in behavior (probably dictates the format for creating an archive, not expanding existing one).

I got a call-back from Apple support, sort of a hand-off or escalation, and was told since the failing zip archives are generated by a third party (likely Microsoft, I say), there is not much Apple can / will do too investigate. The agent could / would not read anything to me about error code 79 (except the message), nor take it further to file a problem report (CF other peoples software is the problem). Which I think is a bit of a dodge, but OK, whatever.

Also, it is not a huge or corrupted archive file here. We're talking about a 260K zip archive of four little PDF files. It's not some huge (maybe bit-corrupted) 500MB archive. It's archives from Avii that fail. And it's not a download issue, I've downloaded this and other archives, only Avii has failed in Archive Utility. It's Avii in its archive generation, and I'll pass that along to Avii support but expect the same song and dance: we don't write the Apple Archive Utility, so we cannot imagine what is going wrong over there at Apple SW. Finger pointing, so far.

At least, unzip utility does work. Apple, study that, maybe make Archive Utility as smart as unzip?

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Answer 3

rj_oregon Author

Level 1

51 points

Oct 2, 2022 7:02 AM in response to rj_oregon

So, just to follow up, I've been in contact with Support today. First suggestion was to reboot to safe mode. Did that. Did not fix.

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Finder, opening some ZIP archives, makes error 79, but unzip command line works OK, says ZIP file is good

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