*.pdf Could not be opened - It may be damaged or use a file format that Preview doesn’t recognise.

If so, (If you were able to test or not), I’d follow these steps:

First, keep a Time Machine backup, if able to:

Back up your Mac with Time Machine - Apple Support

You can even export your mailboxes as another backup option, and which is a good idea, especially if any of your accounts are POP and not IMAP, (You can see this in Mail > Settings > Accounts). As well as if you have custom maillboxes under the On My Mac section in Mail:

Import or export mailboxes in Mail on Mac - Apple Support

Next, disable Mail for all accounts in System Settings > Internet Accounts.

Make sure the Mail app is closed.

Open Finder, while holding the Option key, on the top menu, click Go > Library.

In the Library, open the Mail folder.

Drag the V10 or associated V folder to the Desktop as a copy.

Restart, the. Relaunch the Mail app while holding the Shift key.

Mail should now be empty for the most part.

Next, enable Mail again for your accounts in System Settings > Internet Accounts.

(If you were unable to identify if a specific account caused the issue, I’d enable one account at a time and test before enabling another account).

Otherwise if all is okay, you’re good to go, however if you think you are missing any mailboxes, you can import them from the folder on the Desktop you saved earlier via Mail > File > Import Mailboxes > Apple Mail, then choose the missing mailboxes from one of the alphanumeric folders in the ~/Desktop/Mail/V10 folder.

Otherwise, if all is there, which it usually is, you can just move that folder to the Trash bin.

Hope that helps!

Otherwise, I’d say, if affecting accounts, it could be a preference issue.

If that is the case, (And all works in another user account, etc.), I’d then do the same steps to disable accounts, quit Mail, and this time in the ~/Library, open the Containers folder, move any folder with Mail or com.apple.mail.plist to the Desktop, restart and relaunch the Mail app. (You’ll probably have to set your mail settings again, such as the layout, rules, signatures, etc.).

If that doesn’t fix it, you may need to do other tests, such as in safe mode, or in another user account, which can take time, but reveals a lot as to the possible cause.

Perhaps if the same happens in a new user, and safe mode, and even if this happens with all email accounts, then most likely the operating system needs to be reinstalled:

Start up your Mac in safe mode - Apple Support

Add a user or group on Mac - Apple Support

How to reinstall macOS - Apple Support

Anyhow, hope something here helps!

@DiZoE

You have solved my problem. The issue was that OneDrive had no permissions to download the file on demand; i.e. when i was trying to open a PDF (as you pointed out it was consuming zero memory space on my mac). My expectation was that when i opened the PDF it would automatically download first then try to open it.

The security update is to adopt a white list as you need security policy; unless an application requests permission from the OS by default it has no permissions.

To give Ventura OneDrive Permissions to download on demand you have to

Go into OneDrive and select Preferences (you can find this in the micro tray at the top right (see image)

Then click this button (Download files as you use them) -> this re-confirms it for Ventura.

All my older PDF's now open in Ventura :)

(while i now cannot replicate the error, i can confirm it was the same error message.)

Hey MonicaStoian!

Thanks for the details, will help if able to.

Can you say exactly what happens when you try opening the file in Mail?

Likewise, if you were to drag the file from mail and save in another location, or even to open in another app than Preview can you say what happens?

Do other file formats open just fine?

Does this only happen from one sender? Or from all senders?

Are you able to open these documents on other Mac’s or iOS devices okay?

Thanks, those answers may help. Off the bat I had these articles in mind:

Safety tips for handling email attachments and content downloaded from the Internet - Apple Support

Change Privacy settings in Mail on Mac - Apple Support

Hope that can help us to narrow down the cause!

Background:

I have been scanning documents using a networked folder. The network folder points at a OneDrive Account where the PDF's are deposited in the OneDrive/myScans folder automatically > One drive then automatically syncs these files for me.

All the documents I had scanned on MacOS BigSur were viewable and in good health prior to the upgrade to MacOS Ventura sometime before 18th February 2023 at 12:32. Once I upgraded ALL Pdf's i had scanned prior to this are now unreadable in:

• Safari, Brave, Chrome, Adobe Acrobat DC Reader, Anywhere you can think of.

However....

• Any new documents that i scan to the network folder after the 18th February are readable.
• Documents before the 18th are viewable on Windows, Android and MacOS Big Sur...

I've tried all the above steps they do not work.

• Copying/duplicating files
• I have reinstalled OneDrive, Adobe Acrobat DC Reader
• I have kept up to date Chrome, Brave, Safari and the latest Mac OS as of today: 13.2.1 (22D68) on an i9 mac.

I'm convinced that there is some kind of update 'privacy' related with the OS that believes these PDF's are a threat to the PC and marks them as corrupt.

Please can someone address this urgently as the previous person who declared this probably gave up chasing this and isn't a software engineer like me.

What's changed in file world around PDF's, Security, One Drive in Ventura?

This screenshot compares the two files in get Info

You might want to try using the free Adobe Reader. It usually opens any PDF file without problems. Then find a PDF file in Finder and right click it and select 'Get Info', Then click on Open With....choose Adobe Reader. Also click on the button, 'Change All'

https://get.adobe.com/reader/

Hey again, thanks for all that!

So if you right click any pdf on your Mac > Get Info......what is Open With set to?

If other than Preview I’d change to Preview then select the option to Change All and try again.

Otherwise, since rebuilding the mailbox had a temporary fix, I’d say reindexing it even resetting the Mail V folder to defaults and trying again.

But first are you able to confirm if this happens with ALL the email accounts in the Mail app? (If you have more than one to test with), or just one particular account?

Cheers.

Hey there!

So just to confirm, you’ve changed the default app for pdf’s to Preview, then tested? (I see from the screen shot Acrobat is the default), of course you can right click > Open With > Preview, etc.

I see the location of the files are in ~/Containers, I know Microsoft and other developers use this location. If you move the pdf’s to another location, or duplicate them, do they open? How about if you right click > open?

For the unreadable file, I see it’s using zero disk space, as if it’s only stored with One Drive and not actually downloaded to your Mac, as compared to the readable file, which is using disk space. Perhaps it’s a One Drive syncing issue, or conflict with Ventura.

Are they in fact producing the same error message as the author of this post mentioned?

You can always give Apple Support a call too if you need to as well.

Hey kraggnar!

Thats awesome, well done, and good to know!