diff --git a/fern/products/api-def/openapi/extensions/overview.md b/fern/products/api-def/openapi/extensions/overview.md
index 18722d0bc5..921eb850c3 100644
--- a/fern/products/api-def/openapi/extensions/overview.md
+++ b/fern/products/api-def/openapi/extensions/overview.md
@@ -36,6 +36,7 @@ The table below shows all available extensions and links to detailed documentati
 | [`x-fern-sdk-method-name`](./method-names) | Customize SDK method names |
 | [`x-fern-sdk-group-name`](./method-names) | Organize methods into SDK groups |
 | [`x-fern-sdk-variables`](./sdk-variables) | Set common path parameters across all requests |
+| `x-fern-sdk-namespace` | Namespace schemas to prevent name collisions when combining multiple API specs |
 | [`x-fern-parameter-name`](./parameter-names) | Customize parameter variable names |
 | [`x-fern-property-name`](./property-names) | Customize object property variable names |
 | [`x-fern-retries`](./retry-behavior) | Configure retry behavior for endpoints |
diff --git a/fern/products/cli-api-reference/pages/general-commands.mdx b/fern/products/cli-api-reference/pages/general-commands.mdx
index 27fabe6170..489658f8d9 100644
--- a/fern/products/cli-api-reference/pages/general-commands.mdx
+++ b/fern/products/cli-api-reference/pages/general-commands.mdx
@@ -363,6 +363,8 @@ These commands apply to every Fern project, whether it publishes [docs](/learn/c
   Pulls the latest OpenAPI spec from the specified `origin` in `generators.yml` and
   updates the local spec. Alternatively, you can [automate this process by setting up a GitHub Action](/learn/api-definitions/openapi/sync-your-open-api-specification).
 
+  The local file referenced by the `openapi:` path in `generators.yml` must already exist before running `fern api update`. The command overwrites the file in place — it does not create a new file. If the file is missing, the command outputs `Missing file: <filename>`. To fix this, create an empty placeholder at the expected path (e.g., `touch path/to/openapi.json`) and re-run `fern api update`.
+
   <CodeBlock title="terminal">
     ```bash
     fern api update [--api <api>]