---
title: "Updating Signer on Docker"
description: "How to update Signer on Docker and Docker Swarm: check the installed version, back up, change the lacunasoftware/signer image tag, confirm the new version and know how to roll back."
canonical: "https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/docker/update"
locale: "en"
product: "Signer"
last_updated: "2026-10-22"
---

# Updating Signer on Docker

This page shows how to update an on-premises Signer instance that uses the
[lacunasoftware/signer](https://hub.docker.com/r/lacunasoftware/signer) image, in a container or in a Docker Swarm stack.

## Before you update

1. Check the installed version. Open `https://<your-domain>/api/system/info`. The `productVersion` field shows the version.
1. Read the [changelog](https://docs.lacunasoftware.com/en-us/articles/signer/changelog) of every version between yours and the new one. Look for the versions
   marked as changing the database model.
1. If you are moving from 2.x to 3.x, also read [Updating to 3.x](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/update-30). The 3.x images already
   ship the ASP.NET Core Runtime 10.0.
1. Update the staging environment first. Test sending and signing documents before you update production.
1. Pick a low-usage time. On the first startup, the application updates the database when the new version changes
   the model.

> **Tip**
>
> Use the tag with the exact version, for example `lacunasoftware/signer:3.0.0`. The `3`, `stable` and `latest` tags
> move with each new version. With them, a container restart can bring a version you did not test.

> **Warning**
>
> If you run more than one container, only one of them must update the database. Scale down to one container before
> you update. Alternatively, on every container but one, set `General__AutoUpdateDatabase=false` and
> `General__ProcessBackgroundJobs=false`.

## Backup

1. Back up the database. With the default stack, the database lives in the `sql` volume. With an
   [external database](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/docker/docker-swarm/external-db), back it up in SQL Server.
1. Back up the files: the `files` volume of the default stack or the configured [Blob Storage](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/blob-storage).
1. Keep the encryption key (`signer_encryption_key`) and the environment variables or the `signer.json` file.

See [Persistent data](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/docker/docker-swarm/persistent-data).

## Update a container

1. Pull the new version image:

   ```sh
   docker image pull lacunasoftware/signer:3.0.0
   ```

1. Stop and remove the current container.
1. Run a new container with the new image and the same environment variables and volumes as the previous one.

## Update on Docker Swarm

1. If the service has more than one replica, scale it down to one:

   ```sh
   docker service scale signer_signer=1
   ```

1. In the `signer-stack.yml` file, change the image tag of the `signer` service, for example to
   `lacunasoftware/signer:3.0.0`.
1. Deploy the stack again:

   ```sh
   docker stack deploy -c signer-stack.yml signer
   ```

1. After the service starts, scale back to the number of replicas you used.

> **Note**
>
> In the commands above, `signer` is the stack name. If you deployed with another name, change it in the commands.

## Check the update

1. Open `https://<your-domain>/api/system/info` and check that `productVersion` shows the new version.
1. Follow the log during the first startup. The database update can take a few minutes.
   On Docker Swarm, run `docker service logs signer_signer -f`. For a container, run `docker logs -f <container>`.

If the container does not start and the log shows `PKI SDK License was not loaded successfully`, the application did
not load the PKI SDK license (missing, invalid or expired). Ask Lacuna for an updated license and set it in
`PkiSuite__SdkLicense`.

## If something goes wrong

If the new version has a problem, contact Lacuna support first. If the new version applied database migrations,
switching the image tag back is not enough. Follow the [version rollback](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/rollback) and use the
previous version tag in the step that restores the binaries.

## See also

* [Setup on Docker](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/docker)
* [Docker Swarm](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/docker/docker-swarm)
* [Version rollback](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/rollback)