> For the complete documentation index, see [llms.txt](https://support.skylum.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://support.skylum.com/thumbnails-not-generating-or-showing-as-black-squares.md).

# Thumbnails Not Generating or Showing as Black Squares

{% hint style="warning" %}
**Note:** Some interface details and visuals in this article may differ from the latest version of Luminar for Desktop. To see the current interface, visit the [Luminar for Desktop walkthrough](https://app.gitbook.com/o/ce1mezuaelhjGQ6S9kTM/s/ynrwC8fnGXULbglwsNaw/~/edit/~/changes/156/how-to-use-luminar-neo/luminar-for-desktop-walkthrough).
{% endhint %}

### :thinking: Why This Happens

Image thumbnails are considered as previews of already edited images, as Luminar for Desktop uses cached data and indexing to display your photos quickly, specifically in thumbnails.

### :tools: How to fix it?

You can simply clear Luminar for Desktop's cache with one button. Follow these steps:

{% tabs %}
{% tab title="Windows" %}

1. **Open** Luminar for Desktop
2. Go to **File > Preferences**.
3. Find the **“Catalog cache size"** section within the Preferences window.
4. Click **"Clear cache"**.
   {% endtab %}

{% tab title="macOS" %}

1. **Open** Luminar for Desktop.
2. Go to **Luminar for Desktop > Settings**.
3. Find the **“Catalog cache size"** section within the Settings window.
4. Click **"Clear cache"**.
   {% endtab %}
   {% endtabs %}

{% hint style="info" %}
After clearing the cache, there might be a short delay when viewing previews of already edited pictures as Luminar for Desktop rebuilds them. This is normal.
{% endhint %}

You don't need to do this every day, but consider it regularly to free up space and fix any black thumbnail issues.

<details>

<summary><span data-gb-custom-inline data-tag="emoji" data-code="2753">❓</span>Q&#x26;A Section</summary>

:thinking: **Why is clearing the cache that contains cached previews sometimes important or necessary?**\
Clearing these folders forces Luminar for Desktop to rebuild data from scratch. This is important for:

* 🖼️ **Fixing Display Errors:** Resolves issues where thumbnails/previews are corrupted, missing, outdated, or don't match edits.
* ⚙️ **Resolving Instability:** Can fix freezes or sluggishness if the cached data or index files have become corrupted.

***

**🧹 In which cases should I clear the preview cache on my device?**\
Consider clearing them if you experience:

* 🔄 Thumbnails or previews showing incorrect content, artifacts, or failing to update.
* ❌ Missing thumbnails.

***

**🛡️ Will clearing the folders with cached previews delete my photos or edits?**\
**No**. Clearing the cache **does not delete your original photos or your editing adjustments**. These are stored safely elsewhere in your Catalog and on your hard drive. Luminar will simply regenerate the necessary preview data.

***

**⚠️ Are there any downsides?**\
Yes, temporarily:

* 🐢 **Slower Initial Performance:** Luminar for Desktop will need time to regenerate previews. Performance will return to normal gradually.
* ⏳ **Regeneration Time:** Depending on the size of your catalog, the regeneration process might take some ti

</details>


---

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