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

# E-CFG-003

> Doctor found the OpenAPI spec's relative server mount and VENDO_BASE_URL's path prefix disagree, so every host tool call 404s.

```text config/mount theme={null}
broken: <spec> declares servers[0].url "<mount>" but VENDO_BASE_URL's path is
"<basePath>" — one of them is wrong, and the disagreement 404s every host
tool while every page renders.
```

`<spec>` is your OpenAPI spec's path, `<mount>` is the relative server URL it
declares, and `<basePath>` is the path doctor read out of `VENDO_BASE_URL`.
When `VENDO_BASE_URL` is unset entirely, the message instead reads
`VENDO_BASE_URL is unset` in place of the path comparison, same cause, same
fix.

`check: config/mount` · `error_code: E-CFG-003` · `doctor exits: 1`

## What you're seeing

The app looks perfect. Every page renders and every number the agent quotes
fails, because the client, the server, and the OpenAPI spec disagree about
the deployment's path prefix.

## Why

Your deployment's path prefix has exactly one home: `VENDO_BASE_URL`. A spec
that declares a different relative server mount is the same disagreement by
another route. With no base URL set, the wire learns the bare request
origin instead, so a prefix-free stored path lands one prefix short.

## The fix

Set `VENDO_BASE_URL` to the app's full public URL, prefix included, and pass
that same prefix into the provider.

```bash .env.local theme={null}
VENDO_BASE_URL=https://site.com/maple
```

```tsx app/layout.tsx {1} theme={null}
<VendoProvider baseUrl="/maple/api/vendo">{children}</VendoProvider>
```

If the app isn't actually mounted under a prefix, drop the relative
`servers[0].url` from the spec instead. Re-run `npx vendo doctor`, which
reports this same code if the disagreement remains.

## Related errors

* [E-CFG-001](/production/troubleshooting/e-cfg-001): a missing `.vendo/` file, a different kind of config gap
* [E-WIRE-004](/production/troubleshooting/e-wire-004): the provider mount this base URL feeds into