---
title: Vite Build Manifest Troubleshooting
description: "**Check.** `vite build` stops with an error from `consentManifest`
  that starts with the plugin's name, such as `@c15t/core/build: could not fetch
  the consent manifest from <url> during the build`. The name is
  `@c15t/core/build` for `c15t/build` and `@c15t/vue/vite` for `c15t/vue/vite`.
  `vite dev` logs the same message as a warning and keeps going. The part in
  parentheses names the cause:"
lastModified: "2026-10-10T14:59:21+01:00"
lastAuthor: Kaylee
---
## Why does the build fail to download the manifest?

**Check.** `vite build` stops with an error from `consentManifest` that
starts with the plugin's name, such as
`@c15t/core/build: could not fetch the consent manifest from <url> during the build`. The name is `@c15t/core/build` for `c15t/build` and `@c15t/vue/vite`
for `c15t/vue/vite`. `vite dev` logs the same message as a warning and keeps
going. The part in parentheses names the cause:

|Message|Cause|Fix|
|--|--|--|
|`fetch failed`, with `ENOTFOUND`, `ECONNREFUSED` or another network error|The build cannot reach the backend|Build where the backend is reachable|
|`no response within 10 seconds`|The backend did not answer in time|Check the backend, or build where it is reachable|
|`/manifest responded 404`|The URL is not your project's backend, such as the `https://your-project.inth.app` placeholder or a URL missing its path prefix|Copy the backend URL exactly as Inth shows it, or set `VITE_C15T_BACKEND_URL`|
|`/manifest returned an invalid consent manifest.`|The URL answered with something other than a consent manifest, such as an HTML page|Point `backendURL` at the backend itself, not your site or a dashboard page|

A failed download never reuses an old snapshot. To deploy while the backend
is down, run the build with `C15T_ON_BUILD_ERROR=runtime`. `snapshot` is then
`undefined`, and the browser fetches the policy from the backend at runtime.

Only a build that uses `manifest()` downloads the manifest. The plugin
fetches after Vite has dropped the code the app does not use, so a `hosted()`
or `offline()` build never contacts the backend and never fails this way.

An error or warning that says `no backend URL is set` means the plugin found
no `backendURL` option and no variable. Set `VITE_C15T_BACKEND_URL` (or
`VITE_INTH_PROJECT_URL`) in `.env` or the build environment, or pass the absolute backend URL from your Inth
project. The [troubleshooting guide](/docs/guides/troubleshooting#why-does-the-build-fail-to-download-the-manifest)
lists every message.

A notice that the build `skipped the consent manifest fetch` means the backend
URL is relative, such as `/api/c15t`. Pass the absolute backend URL instead.
With `onBuildError: 'fail'`, this stops the build with `build-time manifests require an absolute upstream URL`.

## Why is snapshot undefined?

**Check.** `snapshot` from `c15t/generated` is `undefined`, and the browser
requests `${backendURL}/manifest` on page load.

**Fix.** `snapshot` is `undefined` when Vite has no policy to serve:

* `consentManifest` is missing from `plugins` in `vite.config.ts`. Without the
  plugin, `c15t/generated` still resolves, but exports `undefined`.
* The fetch failed in `vite dev`, or in a build with
  `C15T_ON_BUILD_ERROR=runtime`. The terminal shows a `could not fetch the consent manifest` warning.
* The backend URL is relative, so the plugin skipped the fetch.
* `consentManifest({ source: 'runtime' })` is set, so the plugin never
  fetches.

Fix the cause, then restart `vite dev` or rebuild. The plugin fetches once
when Vite starts.