> ## Documentation Index
> Fetch the complete documentation index at: https://braintrust.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Topics facets empty due to Skipped status

export const plans_0 = "Any"

export const deployments_0 = "Any"

export const data_plane_version_0 = undefined

export const use_case_0 = "Use case - Topics facets show empty results because all traces have Skipped status"

<Note>
  **Applies to:**

  * Plan - {plans_0}
  * Deployment - {deployments_0}
  * {data_plane_version_0}
  * {use_case_0}
</Note>

## Summary

**Issue:** Topics facets appear empty and traces show a `Skipped` status instead of generating summaries.

**Cause:** `Skipped` means the default Thread preprocessor found no usable conversation text — this happens when traces do not store conversation content on LLM-type spans, which is what the default preprocessor reads.

**Resolution:** Create a custom preprocessor that extracts conversation from your actual trace shape, set it as the project default, and then re-generate topics.

## Resolution steps

### Step 1: Confirm the cause

Open a trace in **Logs** and select the **Thread** tab in the Trace Viewer if the Thread view is empty, the preprocessor is not finding conversation content.

### Step 2: Create a custom preprocessor

1. In **Logs**, open any trace.
2. Select the **Thread** tab.
3. Click the config button.
4. In the **Preprocessor** dropdown, select **+ Custom preprocessor (advanced)**.
5. Enter your preprocessor code, see the [Enable Topics - Write a custom preprocessor](https://www.braintrust.dev/docs/observe/topics/enable#write-a-custom-preprocessor) docs for examples.
6. Enter a name, click **Test** to verify output, then click **Save**.

### Step 3: Set the preprocessor as the project default

1. Navigate to **Settings → Advanced** (under the Project section).
2. Under **Default preprocessor**, select the preprocessor you just created.
3. Click **Save**.

### Step 4: Verify and re-generate topics

1. Open a trace, go to the **Thread** tab, and confirm the conversation now appears.
2. In **Logs**, click the **Topics** button (top right), select a facet, open a trace, and click **Test** in the Topics pane to confirm facet output.
3. In **Topics**, click the three dots menu in the top right and select **Process existing Traces**.
4. Select a **Time range** from the dropdown and click **Process traces**.