Outlook Cannot Find the Path Error When Opening Attachments From Network Drives

You may see an error stating Outlook cannot find the path when trying to open an email attachment. This typically happens when the attachment is saved to a network drive or a mapped drive letter. The error prevents you from accessing files directly from your email.

The problem is caused by Outlook’s security settings and Windows path resolution. Outlook blocks direct access to certain file locations for security reasons. This article explains the cause and provides steps to open your attachments.

You will learn how to change a specific registry setting to allow access. The guide also covers alternative methods to save the file first.

Why Outlook Blocks Attachments on Network Paths

Outlook has a built-in security feature called Object Model Guard. Its purpose is to prevent malicious code from running when you open an email attachment. This feature treats network paths, including mapped drives like Z: and UNC paths like \\server\share, as untrusted locations.

When you double-click an attachment, Outlook tries to open it from its temporary storage location. If the file is linked to a network path, the security model intervenes. It generates the cannot find the path error to stop potential unsafe code execution.

This behavior is consistent across Outlook as part of Microsoft 365, Outlook 2021, and Outlook 2019. The setting is controlled by a registry value, not by a visible option in the Outlook user interface. Changing it requires careful editing of the Windows Registry.

Understanding UNC and Mapped Drive Paths

A Universal Naming Convention path starts with two backslashes followed by a server name. A mapped drive is a letter like H: assigned to a network location. Outlook’s security settings treat both types the same way by default. The error can occur even if you have full Windows permissions to the folder.

Steps to Allow Outlook to Open Network Attachments

The primary fix involves modifying a registry key. Always create a system restore point or back up the registry before making changes. The steps below are for Outlook as part of Microsoft 365, Outlook 2021, and Outlook 2019.

1. Open the Registry Editor
   Press the Windows key + R, type ‘regedit’, and press Enter. Click Yes if prompted by User Account Control.
2. Navigate to the Outlook Security Key
   In the Registry Editor, go to HKEY_CURRENT_USER\Software\Microsoft\Office. Expand the Office folder, then find the folder for your Outlook version. For Microsoft 365 and Outlook 2021, look for ‘16.0’. Inside that, navigate to Outlook\Security. If the Security folder does not exist, right-click the Outlook folder, select New > Key, and name it ‘Security’.
3. Create the AllowUncAccess Value
   Right-click in the right-hand pane of the Security key. Select New > String Value. Name the new value ‘AllowUncAccess’. Double-click this new value and set its Value data to ‘1’. Click OK.
4. Close Registry Editor and Restart Outlook
   Close the Registry Editor completely. Close and restart Outlook for the change to take effect. You should now be able to double-click attachments that point to network locations.

Alternative Method: Save the Attachment First

If you prefer not to edit the registry, use the save method. Right-click the attachment in the email and select Save As. Choose a local folder like your Desktop or Documents. Navigate to that local folder in File Explorer and open the file from there. This method is always safe and does not require configuration changes.

If the Path Error Persists After the Registry Fix

Outlook Still Shows Cannot Find the Path

First, verify the registry value was created correctly. Reopen regedit and check that AllowUncAccess exists under the correct version key with a value of 1. Ensure you have restarted Outlook. If the problem continues, the network path itself may be unavailable. Check the network drive mapping in File Explorer or try accessing the UNC path directly.

Attachment Preview Pane Shows an Error

The preview pane uses the same security rules. Go to File > Options > Trust Center > Trust Center Settings > Attachment Handling. Uncheck the box for ‘Turn off Attachment Preview’ and click OK. This does not fix the core path error but ensures preview works for local files after you save them.

Error Occurs with Specific File Types Only

Some file extensions have additional security restrictions. Executable files like .exe or .bat are blocked regardless of location. The registry fix only applies to documents like .pdf, .docx, and .xlsx. For blocked file types, the only option is to save the file to your local drive first.

Opening Attachments: Security Methods Compared

Item	Save As to Local Drive	Registry Edit (AllowUncAccess=1)
Security Risk	Very Low	Moderate
Convenience	Requires manual save step	Allows direct double-click open
Technical Skill Required	None	Intermediate
Effect on Other Users	Applies only to your actions	Applies to your Outlook profile only
Recommended For	All users, occasional network files	Power users who frequently open from networks

You can now open email attachments saved on network drives. The registry edit for AllowUncAccess provides a direct solution for frequent users. Always save critical files to your local drive as a safe practice to avoid permission issues.

For related settings, review the Trust Center options under File > Options. An advanced tip is to use the Group Policy Editor if you are an administrator managing many computers. The policy path is User Configuration > Administrative Templates > Microsoft Outlook 2016 > Security > Security Form Settings > Programmatic Security.