Error: 0x80071771, The Specified File Could Not Be Decrypted While Accessing A Video File On An External Hard Drive.

Hi Tasos,

Thank you for writing to Microsoft Community Forums.

According to the issue description, it seems that you have encrypted this file/folder/drive with Microsoft Encrypting File System. If you have encrypted this file/folder/drive with Microsoft Encrypting File System on your previous computer/previous Operating System, please note that you will be able to access the encrypted file/folder/drive only with the login of the account you encrypted the file/folder/drive with. Other user accounts won’t be able to access these file/folder/drive. Plug this hard drive into your previous computer/previous Operating System, logon with the account you encrypted the file/folder/drive with, decrypt again by right clicking the file/folder/drive and untick Encrypt contents to secure data in Advanced option.

However, you may try the below methods and check if this helps.

Method 1: Taking Ownership Of The External Hard Drive.

1. Go to This PC > Right-click on the hard drive, in which you are trying to access the AMV video file > Click on Properties.
2. Go to Security tab and click on Edit > A new window pop-up when you click on Edit > Click on Add button under Group or user names > Type Everyone in the box under Enter the object names to select and click on OK.
3. Once you return to the Permissions window, select the Everyone group and put all the checkmarks to the Allow box under Permissions for Everyone section.
4. Click on Apply and OK to save the changes.
5. Now, reopen the Security tab and Click on Advanced button beside to For special permissions or advanced settings.
6. From the Advanced Security Settings window, go to the Permissions tab and click on Change > From, Select User or Group window, type Everyone under Enter the object name to select and the OK button.
7. Next, make sure to check the box associated with Replace owner on subcontainers and objects and click on Apply.
8. With the owner as Everyone, go to the Auditing tab and click on Add.
9. Under the Auditing Entry for the affected volume, select Everyone as Principal, then go to the Basic permission section and check the box associated with Full control.
10. Click on OK > Apply > OK to save all the changes > Restart the computer once and check for the issue.

Method 2: Taking Ownership Through Command Prompt.

• Click on the Start Menu > Search for Command Prompt > Right-click on Command Prompt > Click on Run As Administrator.
• Once the Command Prompt is up and running, type the following command into the Command Prompt window and hit Enter.

cipher /d “full path of the file with the extension”

Note: Make sure to type in the full path of the encrypted file or folder between the quotes.

• Restart the computer after executing the above command and check if you are able to access the files.

Give it a shot and let us know of any changes.