HTTP 430 Request Header Fields Too Large
HTTP 430 is an unassigned, unofficial status code used by Shopify to indicate that request headers are too large to be processed. It is not part of the official HTTP specification — IANA lists 430 as unassigned. The standardized equivalent is HTTP 431 Request Header Fields Too Large.
Quick reference
| Code | 430 |
|---|---|
| Name | Request Header Fields Too Large |
| Category | 4xx Client Errors |
| Specification | IANA Registry (Unassigned) |
| IANA status | Unassigned — unofficial extension code |
| Cacheable | No |
| Client action | Reduce request header size. The standard code for this condition is 431 Request Header Fields Too Large. |
| In-depth guide | HTTP 430 full guide → |
What HTTP 430 means
430 is not an official IANA-assigned HTTP status code. Shopify's platform uses 430 to signal that the incoming request headers exceed Shopify's size limits. Outside of Shopify's infrastructure, 430 is not a recognized code and should not be encountered in standard HTTP communication.
The official standard code for oversized request headers is 431 Request Header Fields Too Large, defined in RFC 6585. If you are seeing 430, it is almost certainly from Shopify or a system that adopted Shopify's non-standard extension. Treat it functionally the same as 431: the request headers are too large.
Common causes of oversized request headers
Cookie accumulation
The most common cause. Browsers accumulate cookies from sites over time. Every request to a domain includes all cookies set for that domain in the Cookie header. As cookies accumulate — from analytics, A/B testing tools, authentication, and session management — the header grows. Exceeding the server's header size limit produces 430 or 431.
Large Authorization or custom headers
JWT tokens in Authorization headers can be large, especially with many claims. Custom API headers carrying metadata can also contribute to total header size. When many large headers combine, the total can exceed the limit.
Third-party scripts setting large cookies
Analytics and marketing tools set cookies on behalf of the site. A single third-party tool may set many cookies, each consuming header budget.
How to fix a 430
- Clear cookies for the domain. In the browser, clear cookies specifically for the domain returning 430. A fresh start without accumulated cookies often resolves the immediate issue.
- Audit cookies set by the application. Review which cookies are set on the domain and their sizes. Remove unnecessary cookies and reduce cookie payload sizes where possible.
- Use session storage instead of cookies for large data. If storing large objects in cookies, move that data to session storage or server-side session management and use a smaller session ID cookie instead.
- Consolidate third-party cookie usage. Each analytics and marketing tool sets its own cookies. Evaluate whether all tools are necessary and consider consolidating.
430 vs 431
FAQ
What does HTTP 430 mean?
HTTP 430 is an unofficial code used by Shopify's platform to indicate that request headers exceed size limits. The official equivalent is 431 Request Header Fields Too Large. Clear cookies for the domain to resolve it.
Is 430 an official status code?
No. IANA lists 430 as unassigned. It is a non-standard extension used by Shopify. Outside of Shopify's infrastructure, 430 is not a recognized HTTP code.
How do I fix a 430 error on a Shopify store?
Clear cookies for the store's domain in your browser. If you are a store owner, audit the cookies being set by your theme, apps, and analytics tools to reduce total cookie size.
What is the difference between 430 and 431?
They describe the same condition — request headers too large — but 430 is Shopify's non-standard code and 431 is the official RFC 6585 status code. If your server needs to signal this condition, use 431.
Related resources
On this site: HTTP 430 — full guide · HTTP 431 Request Header Fields Too Large · HTTP 413 Content Too Large · HTTP 414 URI Too Long · All 4xx client errors
Standards: IANA HTTP Status Code Registry