---
title: Fix "uses unknown component" (DS-S06)
description: reed check rejects a component name that is not in the catalog. Fix the spelling, set the dialect, or import it.
---

## Symptom

`reed check` or `reed build` stops with a line like this:

```txt
  ✗ [DS-S06] content file "guides/setup.mdx" uses unknown component "Tooltips" (not a catalog member and not locally imported)
check failed.
```

The quoted name is the tag exactly as you wrote it. The page itself looked fine in your
editor, and the same markup may have rendered on the platform you migrated from.

## Cause

Reed ships a fixed catalog of 37 components, and every capitalized tag on a page must be
one of them — or be imported by that page. Anything else is `DS-S06`, an error that
fails both `check` and `build`. Reed refuses it deliberately: an unknown tag would
otherwise publish as broken or empty markup.

Three things produce it:

- **A typo or wrong case.** `Tooltips`, `Codegroup`, `Accordian`. Names are
  case-sensitive.
- **A component from another platform.** Mintlify's `RequestExample` or
  `ResponseExample`, for example, have no Reed equivalent and are unknown under every
  dialect.
- **An alias that only exists under a dialect.** Fern's `Cards`, `StepGroup`,
  `TabGroup`, `Code`, `CodeBlocks` and the `StickyTable` / `SearchableTable` /
  `PaginatedTable` family resolve to catalog components only when `content.dialect` is
  `"fern"`. Under the default `"reed"` dialect — and under `"mintlify"` — they are
  unknown.

Lowercase tags such as `<img>` or `<div>` are treated as HTML and never reported by this
check.

## Fix

### 1. Compare the name against the catalog

These are the only names Reed accepts without an import:

```txt
Accordion  AccordionGroup  Aside  Badge  Banner  Callout  Card  CardGroup  Check
CodeBlock  CodeGroup  Columns  Danger  Error  Expandable  File  Files  Folder  Frame
Icon  Info  Launch  Note  Panel  ParamField  ResponseField  Step  Steps  Success
Tab  Table  Tabs  Tiles  Tip  Tooltip  Update  Warning
```

If yours is a misspelling of one of these, correct it. The
[component reference](/docs/reference/components/layout) documents each one's props and
children.

### 2. Set the dialect for migrated content

If the page came from Fern and uses Fern names, declare that in `docs.json` instead of
renaming every tag:

```json
{ "content": { "dialect": "fern" } }
```

The dialect is project-wide. Set the one your MDX was written in — see
[Content dialect](/docs/authoring/dialect). With a dialect set, a component the upstream
platform has but Reed does not is reported with its own message instead of `DS-S06`:

```txt
  ✗ [unsupported-upstream-component] content file "guides/setup.mdx" uses "Prompt", which is unsupported under content.dialect "fern": An AI-assistant chat-prompt widget with no reed equivalent; out of scope per design assumption 12
```

That one cannot be fixed with configuration. Replace the component.

### 3. Replace a component Reed does not have

Pick the nearest catalog component, or plain Markdown, and rewrite the markup. A
Mintlify `RequestExample` wrapping a request, for instance, becomes a plain fenced block
at the top level of the page:

````mdx
```sh
curl https://api.example.com/v1/items
```
````

Content that should stay visible while the reader scrolls goes in an `Aside`. Several
language variants of the same snippet go in a `CodeGroup`, one fence per tab — see
[Format code](/docs/authoring/formatting/code).

Names differ between platforms more often than capabilities do.

### 4. Import it, if you really need your own

If you genuinely need something outside the catalog, a local import is the escape hatch.
Check the catalog first. A page-local `import` exempts that name from the check:

```mdx
import MadeUpWidget from './widget.astro';

<MadeUpWidget foo="bar" />
```

`reed check` only reads the imported name from the `import` statement. It does not
confirm the file exists or compiles, so a broken import passes `check` and fails later, in
`reed build`. An imported component also gets none of the catalog's contract checks, so a
missing prop on it is never reported. See
[MDX pitfalls](/docs/authoring/mdx-pitfalls) for when to reach for it.

## Verify

Run the check again and confirm no `DS-S06` lines remain:

```sh
reed check 2>&1 | grep -c 'DS-S06'
```

Expect `0`. A clean project ends with `check passed.` If you fixed the name by setting a
dialect, read the rest of the `reed check` output too: the dialect also changes how props
on every other page are read, and a new `DS-S03` or `DS-D08` elsewhere is how that shows
up.

## Related

- [MDX pitfalls](/docs/authoring/mdx-pitfalls) — the unknown-component section
- [Content dialect](/docs/authoring/dialect)
- [Diagnostics](/docs/reference/diagnostics) — every `DS-*` code
- [Fix component contract errors](/docs/troubleshooting/component-contract)