Permission Denied: Why Cowork Can't Access Your Files (and How to Fix It)

You pointed Cowork at a folder and it came back with a permission error. The folder is right there, you can see it in Finder or Explorer, and yet Claude is acting like it doesn’t exist. This is not a bug in Cowork so much as a modern OS doing exactly what it was designed to do: keeping software out of your files until you say otherwise. The good news is that the fixes are mostly a few clicks, once you know which door to unlock.

Why This Happens

Modern operating systems treat file access as a privilege that apps have to request and that users have to approve. On macOS, this system is called the Privacy & Security framework. On Windows, the relevant feature is called Controlled Folder Access (part of Windows Security). Both are designed to stop malicious software from silently reading or changing your files. They work, and they work indiscriminately, which means a perfectly trustworthy tool like Cowork gets blocked the same way a piece of malware would until you approve it.

There are a few distinct causes, and each one has a different fix.

macOS: Files and Folders Permission

This is the most common cause on Mac. Apple requires apps to request permission before touching certain standard locations: Desktop, Documents, Downloads, and a few others. If you launched Cowork and immediately pointed it at your Documents folder without approving the permission prompt (or if you clicked “Don’t Allow” by accident), it simply cannot see those files.

How to fix it:

1. Open System Settings (the gear icon, not System Preferences, that’s the old one).
2. Click Privacy & Security in the left sidebar.
3. Scroll down to Files and Folders.
4. Find Claude in the list. If it’s not there, Cowork hasn’t tried to request access yet, try the next section.
5. Enable the toggle for whichever location you need: Desktop Folder, Documents Folder, Downloads Folder, or Removable Volumes.
6. Quit Claude fully (right-click the Dock icon, choose Quit, not just close the window).
7. Reopen Claude and try the task again.

If Claude doesn’t appear in the Files and Folders list at all, the permission prompt may have been dismissed before it could be recorded. Try this: in the Cowork session, ask it to read a specific file in the blocked folder. macOS will prompt again. Approve it, then restart Claude.

macOS: Full Disk Access (for Protected Locations)

A few locations on macOS are protected beyond the standard Files and Folders permission. These include your Mail data, Time Machine backups, and some system directories. If Cowork needs to work in one of those areas, it needs Full Disk Access.

How to fix it:

1. Open System Settings > Privacy & Security > Full Disk Access.
2. Click the plus button and navigate to Claude in your Applications folder.
3. Add it to the list and make sure the toggle is on.
4. Restart Claude.

A word of honest caution: Full Disk Access is a broad grant. You’re telling macOS that Claude can read from almost anywhere. Cowork’s own folder-scoping still applies (it only works inside what you’ve shared in the session), but you should understand what you’re granting at the OS level. See Anthropic’s privacy documentation for how data is handled.

macOS: iCloud and Cloud-Only Files

If your files are stored in iCloud Drive and you have “Optimize Mac Storage” turned on, macOS may have offloaded some files to the cloud to save local disk space. The file appears in Finder with a little cloud icon, but the actual bytes are not on your machine. Cowork cannot read a file that isn’t there.

How to fix it:

1. Open Finder and navigate to the file or folder.
2. Right-click and choose “Download Now” (or click the cloud icon next to the file).
3. Wait for the download to complete. The icon will change from a cloud to a normal document.
4. Try the Cowork task again.

If you work with iCloud-stored files regularly, consider turning off “Optimize Mac Storage” for the folders you use with Cowork: System Settings > Apple ID > iCloud > iCloud Drive > Options.

macOS: OneDrive and Other Sync Services

OneDrive has its own version of the same problem. Files-on-demand means files that aren’t actively synced appear as placeholders. The fix is the same: open the file in its native app or right-click in Explorer and choose “Always keep on this device” for the relevant folder, then retry.

Dropbox and Google Drive can also cause this if you’re using their selective sync features. Check the sync app’s status indicator in the menu bar before assuming it’s a Cowork problem.

macOS: Folder Permission Bits

Less common but worth checking: the folder itself might have restrictive Unix permissions. This usually happens with folders created by another user account or copied from a server.

How to check and fix it:

1. In Finder, right-click the folder and choose Get Info.
2. Scroll to the Sharing & Permissions section at the bottom.
3. Check that your user account has Read & Write permission.
4. If not, click the lock icon, authenticate, and change the permission for your account.

Alternatively, in Terminal: ls -la /path/to/folder will show you the permission bits. chmod 755 /path/to/folder is a reasonable starting point for a folder you own.

Windows: Controlled Folder Access

Windows Defender’s Controlled Folder Access blocks unauthorized apps from writing to protected folders like Documents, Pictures, and Videos. If Cowork tries to write a file to a protected location, it will be blocked silently or with a generic access denied error.

How to fix it:

1. Open Windows Security (search for it in Start).
2. Click Virus & Threat Protection.
3. Click Manage Ransomware Protection.
4. Under Controlled Folder Access, click “Allow an app through Controlled Folder Access.”
5. Click “Add an allowed app” and browse to the Claude executable. It’s typically in C:\Users\<YourName>\AppData\Local\AnthropicClaude\.
6. Save and retry the task in Cowork.

Note that Claude updates can change the executable path. If Cowork starts getting blocked again after an update, re-check this setting and re-add the new path.

Windows: Folder Permissions on NTFS

If you’re working with a folder that was created by an admin account, a company policy, or copied from another machine, your user account might not have write permission on it.

How to fix it:

1. Right-click the folder in Explorer and choose Properties.
2. Click the Security tab.
3. Check if your user account (or the Users group) has Read and Write permissions.
4. If not, click Edit, add your account, and grant the needed permissions.
5. Click Apply and OK.

If your machine is managed by an IT department, they may have locked certain folders intentionally. In that case, the fix is a conversation with IT, not a settings change on your end.

Still Stuck?

If none of the above resolves it, check the Claude Help Center for platform-specific updates. Permission behavior can change with OS updates, and Anthropic publishes notes when a workaround is needed. You can also check Anthropic’s GitHub for open issues related to file access on your platform.

One last thing worth saying plainly: if a fix requires granting broader OS permissions than you’re comfortable with, it’s reasonable to not grant them. Cowork is designed to work within whatever scope you allow. The session-level folder sharing is a second layer of control on top of the OS permissions, so you have more than one place to set limits.