Error Handling in load
Throw error() or redirect() from load to handle failure cases cleanly.
Error Handling in load is a free Sveltejs Academy lesson on CoddyKit. This is lesson 3 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Sveltejs Academy learning path, and your progress syncs across the web and the CoddyKit app. The Sveltejs Academy course includes 4 lessons in total.
Throwing Errors
Use error() from @sveltejs/kit to send a controlled HTTP error.
import { error } from "@sveltejs/kit";
if (!post) error(404, "Post not found");Status Code
The first argument is the HTTP status code (404, 401, 500, etc.).
Error Message
The second argument is a human-readable message displayed by error pages.
Redirects
Use redirect() to send the user elsewhere instead of an error.
import { redirect } from "@sveltejs/kit";
if (!session) redirect(302, "/login");Expected Errors
Calls to error() are expected errors; they show the message you provided.
Unexpected Errors
Uncaught throws become unexpected errors. Their messages are hidden from clients for security.
Custom Error Pages
Create +error.svelte at the root or per route for tailored error UI.
Recoverable Errors
Catch errors inside load and return fallback data when degradation is preferred over error pages.
Try/Catch
Wrap risky calls in try/catch to handle them gracefully.
try { data = await fetch(...) } catch (e) { data = []; }Loading State
Use streaming (Promises in returned object) for partial loading states instead of throwing.
Logging
Log errors centrally via handleError in hooks.server.js.
Quick Check
What does throw error(404) do?
Recap
Use error() for expected failures and redirect() to send users elsewhere from load.
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Frequently Asked Questions
Is the “Error Handling in load” lesson free?
Yes — the full text of “Error Handling in load” is free to read here on the web. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Sveltejs Academy course, upgrade to CoddyKit PRO. The Sveltejs Academy course includes 4 lessons in total.
What will I learn in “Error Handling in load”?
Throw error() or redirect() from load to handle failure cases cleanly. You practise Sveltejs Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Sveltejs Academy?
No prior experience is required. Sveltejs Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 3 of 4.
How long does the “Error Handling in load” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Sveltejs Academy lesson?
Yes. Every Sveltejs Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- +page.js load Function
- Returning Data and Using $page.data
- Error Handling in load
- +page.server.js for Server-Only Logic