Transaction failed when using LXD | Solution

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Transaction failed when using LXD | Solution

LXD is a powerful tool for managing system containers. However, it is still prone to an occasional hiccup. One common issue our users have reported is this error message:

Linux Filesystem Error: Transaction failed when using LXD

This error usually appears during operations like creating containers, launching instances, or updating packages within containers. Furthermore, it points to deeper issues with the underlying storage backend, such as ZFS, Btrfs, or LVM.

This blog will examine the causes, solutions, and preventive tips to help you resolve this error and maintain a stable LXD environment.

Different LXD Container Types

LXD supports two types of containers:

• Privileged Containers:

  These run as root and have elevated access. They are insecure and prone to escape mechanisms. Use only if necessary.
• Unprivileged Containers (default):

  These run inside a user namespace, restricting root access and leveraging AppArmor or SELinux for protection. While more secure, these protections can interfere with certain package operations, often causing the “transaction failed” error.

In many cases, temporarily switching a container to privileged mode helps complete pending updates, after which you can revert it to its safer unprivileged state.

What Causes the “Transaction Failed” Error?

This error is usually caused by one of these issues:

• If a container or virtual machine is actively using a storage pool, LXD may be unable to modify or delete it. Misconfigurations or corruption in the pool’s metadata can also cause failures. If you’re new to storage pool setup or need a refresher, refer to our guide on how to create a storage pool in LXD.
• Improperly configured ZFS pools, missing ZFS tools, or referencing incorrect pool names can result in transaction failures.
• Kernel panics, network drops, or resource exhaustion during operations can halt a transaction mid-process.
• Corruption in LXD’s internal database might block operations like storage pool updates or container management.

Step-by-Step Solution

1. First, check the current state of the containers:

   lxc list

   This will display something like:

   +——————+———+———————-+———————————————–+———–+———–+
   | NAME | STATE | IPV4 | IPV6 | TYPE | SNAPSHOTS |
   +——————+———+———————-+———————————————–+———–+———–+
   | archbox | RUNNING | 10.83.200.161 (eth0) | fd32:66d0:ec52:7d50:216:3eff:fe9d:h205 (eth0) | CONTAINER | 0 |
   +——————+———+———————-+———————————————–+———–+———–+
   | centos-6 | STOPPED | | | CONTAINER | 0 |
   +——————+———+———————-+———————————————–+———–+———–+
   | centos-7 | STOPPED | | | CONTAINER | 0 |
   +——————+———+———————-+———————————————–+———–+———–+
   | centos-8 | RUNNING | 10.83.200.129 (eth0) | fd32:66d0:ec52:7d50:216:3eff:fe6c:g3ed (eth0) | CONTAINER | 1 |
   +——————+———+———————-+———————————————–+———–+———–+
   | debian-8-jessie | STOPPED | | | CONTAINER | 0 |
   +——————+———+———————-+———————————————–+———–+———–+
   | debian-9-stretch | STOPPED | | | CONTAINER | 0 |
   +——————+———+———————-+———————————————–+———–+———–+
   | debian-test | STOPPED | | | CONTAINER | 3 |
   +——————+———+———————-+———————————————–+———–+———–+
   | fedora-33 | RUNNING | 10.83.200.41 (eth0) | fd32:66d0:ec52:7d50:216:3eff:fe8c:4078 (eth0) | CONTAINER | 0 |
   +——————+———+———————-+———————————————–+———–+———–+
   | gentoo | STOPPED | | | CONTAINER | 0 |
   +——————+———+———————-+———————————————–+———–+———–+
   | gui1604 | STOPPED | | | CONTAINER | 0 |
   +——————+———+———————-+———————————————–+———–+———–+
   | gui-1804-gimp | RUNNING | 10.83.200.28 (eth0) | fd32:66d0:ec52:7d50:216:3eff:gea3:7da8 (eth0) | CONTAINER | 0 |
   +——————+———+———————-+———————————————–+———–+———–+
   | opensuse-15-1 | STOPPED | | | CONTAINER | 1 |
   +——————+———+———————-+———————————————–+———–+———–+
   | oracle-7 | STOPPED | | | CONTAINER | 0 |
   +——————+———+———————-+———————————————–+———–+———–+

   If you encounter issues like “instance is already running,” check out our troubleshooting guide for LXC instance startup errors.
2. Then, check the current privilege mode by running:

   lxc config get centos-8 security.privileged
   
   lxc config get opensuse-leap security.privileged
   
   
3. Now, enable privileged mode for containers experiencing the issue:

   lxc config set centos-8 security.privileged true
   
   lxc config set opensuse-leap security.privileged true
   
   
4. Then, apply the updated security profile:

   lxc restart centos-8
   
   lxc restart opensuse-leap
   
   
5. Now, use the corresponding package manager to perform updates:
   • For CentOS:

     lxc exec centos-8 bash
     
     # dnf update
     
     # exit
     
     
   • For openSUSE:

     lxc exec opensuse-leap bash
     
     # zypper up
     
     # exit
     
     
   • After updates, restore secure settings:

     lxc config set centos-8 security.privileged false
     
     lxc config set opensuse-leap security.privileged false
     
     
   • Then, restart again to apply changes:

     lxc restart centos-8
     
     lxc restart opensuse-leap
   • Finally, verify the configuration:

     lxc config get centos-8 security.privileged

Bonus Tips

Here are some bonus tips from our experts to avoid this error in the future:

• Avoid abrupt service stops. Use `systemctl restart lxd` instead of killing processes.
• Back up LXD configurations regularly. Export container settings and internal databases.
• Use built-in tools for storage management. Avoid manual ZFS operations unless necessary.
• Monitor system resources. Ensure the storage pools have enough space and are healthy.

If you’re running into “permission denied” errors while installing LXD via Snap, you’re not alone. This is a common roadblock, and we’ve explained how to fix it in this detailed LXD installation guide.

Similarly, if you need to transfer files between the host and container for debugging or configuration purposes, refer to our walkthrough on copying files from LXC containers to the host system.

[Need assistance with a different issue? Our team is available 24/7.]

Conclusion

The “Transaction failed” error in LXD is most often rooted in storage backend issues, privilege restrictions, or internal configuration problems. With the above tips, we can resolve most of these problems without losing containers or resorting to reinstallation.

In brief, our Support Experts demonstrated how to fix the “ Transaction failed when using LXD” error.