Error "this file cannot be opened because you do not have permission to view it. To view or change permissions...

Rather than manual permissions changes—which is seemingly what caused this—I’d look to use the following:

Resolve issues caused by changing the permissions of items in your home folder - Apple Support

Permissions are fairly gnarly when configured correctly and as macOS expects, and wrong permissions can hose access in unexpected ways, whether it’s in the file, or on the directory.

I’ve corrupted systems using -r recursion and errant commands. Syntax like /Volumes/ExternalHD/myFiles/ shown works, but a path like /Volumes/External HD/myFiles/ (note the space) might not have the intended effect. Best case, it fails. Worst, it clobbers something unexpected.) i’d encourage double-quoting target paths, if the spec might (will?) contain a character needing an escape. (Experienced users know this lesson, and inexperienced and incautious users unfortunately learn about this. I didn’t do much damage, when I learned about this. Thankfully. I’ve seen some gonzo corruptions from this, though.) Use “/Volumes/External HD/myFiles/“ — and with vertical double quotes, not the angled quotes the forum software will here show.

Along the lines of what MrHoffman wrote, try dragging one of the files you are unable to read from the external hard disk into your Home folder or one of its subdirectories. Desktop for example. When doing that hold an option key to make sure you are creating a copy and not an alias. You can even eject the external hard disk drive to make doubly sure.

Attempt to open that file—the one on your Desktop, and reply with your results.

If you are unable to open that file, then Resolve issues caused by changing the permissions of items in your home folder - Apple Support really ought to fix it. That Support document's applicability is limited to one's Home folder and its contents, and probably won't help if a file resides elsewhere (such as an external disk). For that, rcprado's instructions should work, but manipulating copies within your Home folder is a more conservative approach since it leaves the external hard disk's contents untouched.

terrylee5 wrote:

I get the same error. after rebooting MacBook access is granted again. later the same issue starts all over again. Why?

If you haven’t been altering your system protections on these files and directories, your issue probably isn’t related to this one, and it would be helpful to avoid confusion to please start your own thread.

Please download and run and post the output of EtreCheck in that new thread. Open a new reply, press the button that looks like a printed page to get a text input box big enough to paste the hardware and software configuration report here. Please also indicate the path to these files, if not a directory or subdirectory under /Users somewhere. Under your login directory or subdirectory, or a location somewhere else in the file system.

Usual suspects here are add-in apps; add-on cleaners, add-on anti-malware, add-on anti-virus.

If you don’t have add-ins and you have been making changes, please post the EtreCheck (which includes details such as macOS version), please indicate where these problematic files are located if not under /Users in a directory or subdirectory somewhere, and please stop making these protection changes, and please run the protection-reset mechanism mentioned earlier:

Resolve issues caused by changing the permissions of items in your home folder - Apple Support

I can only think it has to do with permissions because I've been changing valuable files permissions' to read only and locking it so that the files dont get over-written or deleted. Can I not do that?

You can certainly do it, and therein lies the problem. If you do it wrong you can lock yourself out of fixing it. I've managed to mess up Permissions in a horrendous manner that Apple insisted was impossible. Having done it anyway, it proved just as impossible to fix. The solution required erasing the affected Mac.

Whatever you did, undo it, assuming you can. Change those file permissions to read / write, and "apply to enclosed items" if appropriate. It sounds like you did that to files on an external hard disk drive, so at least that didn't affect your User Account. If it did you might be facing the same fate I encountered.

To lock files so you don't inadvertently delete them, do the latter part of your quote above: merely set the "locked" bit in Get Info. Of course that's easily bypassed, but that's by design. It will prevent inadvertently overwriting or deleting something by presenting a dialog box.

In addition to the above: your defense against errant deletions, overwrites, corruptions, and other data misadventures... is backups; consistent, scheduled, robust backups.

If you’re working with source code or similar, an additional defense is a distributed source code control system, and frequent, routine, rote, source code check-ins.

You can ONLY fix this using terminal

and it is easy, dont worry.

First, keep in mind that there is 2 different settings for that (but the GUI confuses the user a lot)

1) Permissions: read, write

2) Ownership: user, groups

I am pretty sure the problem is about ownership, but this is not explict on the MacOS finder GUI permisssions and it messes this with users... and when we try to fix one, we damage the other

But using terminal this can easily be fixed/corrected

(PS: about "lock": its another flag, which protect the files from being changed [either permissions, or ownership])

For this to work, files must be Unlocked

we are going to to this on terminal too.

Here is the recipe:

For me to help you, i am going to create a fake/fiction similar scenario for explanations purpose:

Lets suppose/consider that the files and subdirectories that you want to fix access are on /Volumes/ExternalHD/myFiles

Open Terminal:

1) once there, lets remove the "lock" flag (if any was set) from there to the most deep directory file inside there (recursively)

type:

sudo chflags -R nouchg /Volumes/ExternalHD/myFiles/

The command above will remove the "lock" flags from all files inside the current diretory and recursively to all files and directories under it

On this example, this means everything inside:

/Volumes/ExternalHD/myFiles

will have the "lock" flags removed

After it finishes (will take about 5 to 60 or more seconds depending on how many files may be inside there.. just wait it finishes)

2) Now you have to take ownership of that files.

This is how, on terminal, type:

sudo chown -R myusername:staff /Volumes/ExternalHD/myFiles/

(where "myusername" is your MacOS Unix username. So change it to the corresponding login username of your user, as shown under /Users/ folder)

If needed, you can check/verify what your Unix username is, by typing at the terminal this command:

whoami

It is done.

now you can use Finder as always to move, copy, delete or organize the files inside that directory,

without any other problem

FWIW and if you’re not entirely comfortable with protections and ownerships, use a separate and purpose-created login. Using -r over there (and while still within your ~ home directory) can or will trash (other) macOS per-user directories and files, but that won’t harm your login.

I really don’t like mixing sudo and -r switches around any data that I care about, and I know how it works.

A separate disk (akin to rdprado) can also limit the sudo with -r damage, depending on what happened. And here, I’d suspect the involvement of ownership and protection on the parent directory for the file(s) in question. If y’all want us to look at that, post the ls -aled@ of the directory, and the ls -ale@ of the file(s), as a start.

I get the same error. after rebooting MacBook access is granted again. later the same issue starts all over again. Why?