When a NoActiveThemeException is triggered it's because there is no active theme selected.
To select an active theme, you have at least 2 choices.
If you are using the HarmonyAdminBundle, you just need to the Themes page to activate an installed theme.
To manually set an active_theme you must define it directly in the next configuration file:
{% code-tabs %} {% code-tabs-item title="config/packages/liip_theme.yaml" %}
liip_theme:
active_theme: 'acme-theme'{% endcode-tabs-item %} {% endcode-tabs %}
{% hint style="warning" %}
In the above example this means the acme-theme is already installed in your application.
{% endhint %}