> For the complete documentation index, see [llms.txt](https://docs.portainer.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.portainer.io/sts/faqs/known-issues/image-not-found-on-registry-error-when-upgrading-from-ce-to-be-or-self-updating-on-synology-nas.md).

# "Image not found on registry" error when upgrading from CE to BE or self-updating on Synology NAS

{% hint style="info" %}
**Affected versions:** 2.17.0 and above
{% endhint %}

#### Issue Description

When running an in-app upgrade within Portainer that is running on a Synology NAS, users may receive an error "Image not found on registry".

#### Cause

Our team is currently investigating the cause of this issue, but we suspect this is a consequence of Synology's custom Docker build.

#### Workaround

The workaround for this is to follow the legacy upgrade steps found in the [Portainer documentation](/sts/start/upgrade.md) and follow the manual steps option for your environment. This will guide you through the steps to update your Portainer install.

Some users have also reported success with [manually pulling](/sts/user/docker/images/pull.md) the missing image first, then attempting the in-app upgrade.

You can find more details on this issue in the [GitHub Issue](https://github.com/portainer/portainer/issues/8590).