---
title: "Signer - Checking the system logs on Docker"
description: "How to check Signer logs on Docker: the image writes to standard output, which Docker registers as service logs, plus the SQL Server and Nginx logs."
canonical: "https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/docker/docker-swarm/check-logs"
locale: "en"
product: "Signer"
last_updated: "2026-10-22"
---

# Signer - Checking the system logs on Docker

The Docker image for [Signer](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/docker) sends its logs to the standard output, which in turn gets registered
by Docker as service logs. To check the *signer* service logs:

```sh
docker service logs signer_signer
```

To follow the log continuously, use the `-f` flag:

```sh
docker service logs signer_signer -f
```

> **Note**
>
> On the commands shown on this article, the leftmost `signer` is the name of the stack, while the rightmost part is the name
> of the service (in the case above, the *signer* service). If you deployed your stack with another name, say *dropsigner*, you
> would need to replace the leftmost `signer` on the commands shown here with the name of your stack (e.g. *dropsigner_signer*).

You can also check the SQL Server logs:

```sh
docker service logs signer_sql
```

And also the Nginx logs:

```sh
docker service logs signer_nginx
```

## Error with a code on screen

When an unexpected error happens, Signer shows this message to the user:

> An unexpected error has occurred. Please contact technical support and enter the code 62BE3B.

The code has six hexadecimal characters and is random. Signer generates a new code for each error. At the same
moment, it writes to the log an `Error` level line with the same code, followed by the full exception:

```text
Unhandled exception -- code: 62BE3B
```

To find the error, search the service log for the code. Replace `62BE3B` with the code the user reported and adjust
the period in `--since`:

```sh
docker service logs signer_signer --since 24h 2>&1 | grep -A 40 62BE3B
```

Send Lacuna support:

1. The code and the approximate date and time of the error.
1. The log excerpt with the code line and the exception that follows it.
1. The Signer version (the `productVersion` field of `/api/system/info`).
1. What the user was doing when the error happened (screen, action and, if any, the document ID).

> **Note**
>
> Expected errors, such as a data validation, show their own message and carry no such code.

## See also

* [Installing Signer on Docker](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/docker/docker-swarm)
* [Enabling SSL on Docker](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/docker/docker-swarm/enable-ssl)
* [Using an external database on Docker](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/docker/docker-swarm/external-db)
* [Persistent data (backup considerations)](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/docker/docker-swarm/persistent-data)
* [Using a stack with GrantID](https://docs.lacunasoftware.com/en-us/articles/signer/on-premises/docker/docker-swarm/internal-grantid)