How do I fix: 🔍 Why This Happens?

The primary reason for this error is that the cryptsetup tool requires elevated privileges to unlock and manage encrypted devices. When Ubuntu 18.04 updates, the default policy for cryptsetup changes, causing the 'Operation not permitted' error.Another possible cause could be a mismatch between the

How do I fix: Update cryptsetup and modify system configuration?

Step 1: Open a terminal as an administrator (sudo command) or log in to your user account using an elevated shell.Step 2: Run the following command: `sudo apt-get update && sudo apt-get install -y cryptsetup`Step 3: Modify the system's configuration files to ensure the correct UUID is used for the e

Software⏱️ 3 min read📅 2026-06-11

How to Fix: Error unlocking /dev/sdb1: Failed to activate device: Operation not permitted

Error unlocking /dev/sdb1: Failed to activate device: Operation not permitted after Ubuntu 18.04 update.

Quick Answer: Try disabling the LUKS encryption and re-enabling it, or use the `cryptsetup` command with the `-f` option to force the decryption process.

📋 Table of Contents

🔍 Why This Happens
🛠️ Step-by-Step Verified Fixes
💡 Conclusion

Error unlocking /dev/sdb1: Failed to activate device: Operation not permitted occurs after updating Ubuntu 18.04, affecting users who rely on encrypted disks for data storage.

This frustrating issue can be resolved by following the steps outlined in this troubleshooting guide.

🔍 Why This Happens

The primary reason for this error is that the cryptsetup tool requires elevated privileges to unlock and manage encrypted devices. When Ubuntu 18.04 updates, the default policy for cryptsetup changes, causing the 'Operation not permitted' error.
Another possible cause could be a mismatch between the disk's UUID and the one stored in the system's configuration files.

🛠️ Step-by-Step Verified Fixes

Re-run cryptsetup with elevated privileges

Step 1: Open a terminal as an administrator (sudo command) or log in to your user account using an elevated shell.
Step 2: Run the following command: `sudo cryptsetup unlock /dev/sdb1`
Step 3: Enter the passphrase for the encrypted disk when prompted.

Update cryptsetup and modify system configuration

Step 1: Open a terminal as an administrator (sudo command) or log in to your user account using an elevated shell.
Step 2: Run the following command: `sudo apt-get update && sudo apt-get install -y cryptsetup`
Step 3: Modify the system's configuration files to ensure the correct UUID is used for the encrypted disk. The exact steps may vary depending on your distribution and system configuration.

💡 Conclusion

By running the primary fix method or updating cryptsetup and modifying system configuration, users can resolve the 'Operation not permitted' error and regain access to their encrypted disks.

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