sveltejs/kit · error · Error

Multiple layout component files found in ${routes_base}${rou

Error message

Multiple layout component files found in ${routes_base}${route.id} : ${path.basename(existing_file)} and ${file.name}

What it means

SvelteKit's route scanner requires exactly one layout component per route directory. When create_manifest_data's walk finds a second +layout.svelte in the same route directory, it throws an error naming both conflicting files via duplicate_files_error('layout component', ...).

Source

Thrown at packages/kit/src/core/sync/create_manifest_data/index.js:313

				function duplicate_files_error(type, existing_file) {
					return new Error(
						`Multiple ${type} files found in ${routes_base}${route.id} : ${path.basename(
							existing_file
						)} and ${file.name}`
					);
				}

				if (item.kind === 'component') {
					if (item.is_error) {
						route.error = {
							depth,
							component: project_relative
						};
					} else if (item.is_layout) {
						if (!route.layout) {
							route.layout = { depth, child_pages: [] };
						} else if (route.layout.component) {
							throw duplicate_files_error('layout component', route.layout.component);
						}

						route.layout.component = project_relative;
						if (item.uses_layout !== undefined) route.layout.parent_id = item.uses_layout;
					} else {
						if (!route.leaf) {
							route.leaf = { depth };
						} else if (route.leaf.component) {
							throw duplicate_files_error('page component', route.leaf.component);
						}

						route.leaf.component = project_relative;
						if (item.uses_layout !== undefined) route.leaf.parent_id = item.uses_layout;
					}
				} else if (item.is_layout) {
					if (!route.layout) {
						route.layout = { depth, child_pages: [] };
					} else if (route.layout[item.kind]) {

View on GitHub (pinned to 03f1687fe6)

Solutions

1. Remove one of the conflicting layout component files in that route directory
2. If you intended a named layout, ensure it lives in a different directory or rename so only one layout component remains per route
3. Re-run `vite dev`/`svelte-kit sync` after cleanup to confirm the manifest builds

Example fix

# before
src/routes/+layout.svelte
src/routes/+layout@alt.svelte

# after (keep one)
src/routes/+layout.svelte

import { readdirSync } from 'node:fs';
const files = readdirSync('src/routes', { recursive: true });
for (const dir of new Set(files.map((f) => f.split('/').slice(0, -1).join('/')))) {
  const layouts = files.filter((f) => f.startsWith(dir) && /\+layout(@[^/]+)?\.svelte$/.test(f));
  if (layouts.length > 1) throw new Error(`duplicate layout component in ${dir}: ${layouts}`);
}

When it happens

Trigger: Two layout component files resolve to the same route id, e.g. both `+layout.svelte` and `+layout@foo.svelte` (a named layout usage) present in one directory, or case-variant duplicates on case-insensitive filesystems.

Common situations: Copying a named-layout example (+layout@main.svelte) into a folder that already has +layout.svelte; merging branches that each added a layout; file renames that left an old layout behind.

Related errors

• Multiple page component files found in ${routes_base}${route
• Mismatched route config for ${route.id} — the +page and +ser
• No matcher found for parameter '${name}'${file ? ` in ${file
• Multiple ${item.kind} layout module files found in ${routes_
• Multiple ${item.kind} page module files found in ${routes_ba

AI-assisted analysis of sveltejs/kit@03f1687fe6 (2026-09-02). Data as JSON: /api/errors/d8c96c6f12f153e2. Report an issue: GitHub.