No stories found error in Storybook core server when story glob matches no files

Answer

Storybook’s deduplication rule is: keep the first story encountered during loading and skip any later story that has the same ID (kind + story name). The loading order is determined by the sequence of entries in the stories array of .storybook/main.js, followed by alphabetical expansion of each glob pattern. If duplicate IDs are found, Storybook logs a warning to the console (e.g., Duplicate story ID detected: <id>. Skipping later story.) and does not show the duplicate in the Manager UI.

For UI presentation, the default sort order is alphabetical by the story’s kind (the story name) unless a custom storySort is defined in the preview configuration. File‑path order is used only internally to make loading deterministic; it does not affect the UI order.

When the story glob matches no files, Storybook shows the "No stories found" empty state and performs no deduplication because there are no stories to process.

Confirmed facts (based on Storybook’s current behavior)

• Deduplication retains the first‑loaded story; later duplicates are skipped.
• A console warning is emitted for each duplicate ID detected.
• The Manager UI does not display any visual indicator of deduplication beyond the missing duplicate story.
• Default UI sorting is alphabetical by story name; storySort can override this.
• If the glob yields zero files, the empty state appears and no duplicate warnings are logged.

Likely explanation (why this design)

The loading‑order‑first rule provides a deterministic, predictable outcome without requiring additional configuration. Alphabetical UI sorting gives developers a familiar, consistent ordering that is independent of the underlying file system or builder, while still allowing customization via storySort when a different order is desired.

Steps to verify the behavior in your project

1. Create two story files that share the same kind and story name (thus the same ID) and ensure both match a glob in .storybook/main.js.
2. Start Storybook (npm run storybook) and open the browser console.
3. Confirm that only one instance of the story appears in the Manager UI and that a duplicate‑ID warning is logged.
4. Temporarily remove or rename all files so the glob matches zero files, restart Storybook, and verify that the "No stories found" empty state appears with no duplicate warnings.
5. Add a custom storySort function (e.g., sort by file path) and observe that the UI order changes while deduplication still retains the first‑loaded story.

Missing diagnostic detail

The exact behavior can vary between Storybook 6.x and 7.x releases and between builders (Webpack vs Vite). If you observe different results, please specify your Storybook version and the builder you are using so the recommendation can be adjusted if needed.