janhq/jan · error · Error

LlamaCpp extension not found

Error message

LlamaCpp extension not found

What it means

Thrown in the `updateBackend` path when `ExtensionManager.getByName('llamacpp-extension')` returns null AND no extension in `listExtensions()` matches by constructor-name containing 'llamacpp' or type-string containing 'inference'. The llamacpp extension is the only provider of backend-update capability, so its absence blocks the whole flow.

Source

Thrown at web-app/src/hooks/useBackendUpdater.ts:312

      // Get llamacpp extension instance
      const allExtensions = ExtensionManager.getInstance().listExtensions()
      const llamacppExtension =
        ExtensionManager.getInstance().getByName('llamacpp-extension')

      let extensionToUse = llamacppExtension

      if (!llamacppExtension) {
        // Try to find by type or other properties
        const possibleExtension = allExtensions.find(
          (ext) =>
            ext.constructor.name.toLowerCase().includes('llamacpp') ||
            (ext.type &&
              ext.type()?.toString().toLowerCase().includes('inference'))
        )

        if (!possibleExtension) {
          throw new Error('LlamaCpp extension not found')
        }

        extensionToUse = possibleExtension
      }

      if (
        !extensionToUse ||
        !('getSettings' in extensionToUse) ||
        !('updateBackend' in extensionToUse)
      ) {
        throw new Error('Extension does not support backend updates')
      }

      const extension = extensionToUse as LlamacppExtension

      // Use the exact target backend from checkBackendForUpdates if available,
      // to avoid mismatches between old/new backend name formats
      let targetBackendString = updateState.updateInfo.targetBackend

View on GitHub (pinned to fad3f12a14)

Solutions

1. Confirm the llamacpp extension is installed and enabled in Settings > Extensions.
2. Restart the app so extensions re-register.
3. Check the extension's registered name matches 'llamacpp-extension' (or update the fallback matcher).
4. Ensure ExtensionManager initialization completed before invoking updateBackend.

Example fix

// before
const llamacppExtension = ExtensionManager.getInstance().getByName('llamacpp-extension')
if (!llamacppExtension) {
  const possibleExtension = allExtensions.find((ext) =>
    ext.constructor.name.toLowerCase().includes('llamacpp') ||
    (ext.type && ext.type()?.toString().toLowerCase().includes('inference'))
  )
  if (!possibleExtension) {
    throw new Error('LlamaCpp extension not found')
  }
}

// after
const llamacppExtension = ExtensionManager.getInstance().getByName('llamacpp-extension')
if (!llamacppExtension) {
  const possibleExtension = allExtensions.find((ext) =>
    ext.constructor.name.toLowerCase().includes('llamacpp') ||
    (ext.type && ext.type()?.toString().toLowerCase().includes('inference'))
  )
  if (!possibleExtension) {
    throw new Error(
      'LlamaCpp extension not found. Install/enable it in Settings > Extensions and restart.'
    )
  }
}

const ext = ExtensionManager.getInstance().getByName('llamacpp-extension')
if (!ext) {
  toast.error('LlamaCpp extension missing', { description: 'Enable it in Settings > Extensions and restart.' })
  return
}

function isLlamacppExtension(ext: unknown): ext is LlamacppExtension {
  return !!ext && typeof (ext as any).getSettings === 'function'
}

try {
  const ext = ExtensionManager.getInstance().getByName('llamacpp-extension')
  if (!isLlamacppExtension(ext)) {
    toast.error('LlamaCpp extension not found', { description: 'Install/enable it and restart.' })
    return
  }
  // proceed
} catch (error) {
  console.error('updateBackend:', error)
  throw error
}

When it happens

Trigger: The llamacpp extension is not installed, not registered under the expected name 'llamacpp-extension', and its constructor/type strings changed so the fuzzy fallback fails. Common after an app upgrade that renamed the extension or changed its registered name.

Common situations: Extension renamed in a new build (e.g. 'llamacpp' vs 'llamacpp-extension'); extension disabled/uninstalled; ExtensionManager not yet populated at the time of the call (timing/init race).

Related errors

• Extension does not support backend updates
• Backend update failed: ${result.reason}
• Backend update failed
• Invalid backend string: ${targetBackendString} supplied to u
• Invalid backend string format: "${targetBackendString}". Exp

AI-assisted analysis of janhq/jan@fad3f12a14 (2026-08-12). Data as JSON: /api/errors/712b960a0e3e2f74. Report an issue: GitHub.