# HOST131: Response headers rejected

## What this means[​](#what-this-means "What this meansへの直接リンク")

A proxy in front of the store rejects the server's responses for having too many headers.

A cache or proxy layer (commonly Varnish) enforces a limit on response header count or size. The store's lightweight endpoints fit, but full API responses exceed the limit and come back as 503s from the proxy, not from WordPress. The limit must be raised on that layer.

## What to do[​](#what-to-do "What to doへの直接リンク")

Export diagnostics and contact support. Retry after making the change above; retrying without it will fail the same way.

## Your data[​](#your-data "Your dataへの直接リンク")

No order or product data is affected.

## Troubleshoot[​](#troubleshoot "Troubleshootへの直接リンク")

1. On Varnish, raise http\_max\_hdr (header count) and http\_resp\_hdr\_len / http\_resp\_size (sizes).
2. Ask the host which proxy layer returns the 503 — the WordPress error log will show nothing because the request never fails there.
3. A quick check: the store's /wcpos/v2/ping answers fine while data endpoints 503.

## Where to look[​](#where-to-look "Where to lookへの直接リンク")

When WCPOS can save this error, it is recorded on the device that raised it. Open **Store health → Logs** (the heart-pulse icon at the bottom of the navigation drawer), find the entry marked with this code and expand it: the expanded row shows the plain-language reason and the context captured at the moment of failure. For a store request, that context may include the server’s own error code (`serverCode`), the HTTP `status` or the `endpoint`; the fields shown depend on where the failure occurred. When reporting a problem, use **Copy debug info** at the top of the Logs screen (**Share debug info** on phones and tablets) rather than screenshots: it bundles the app version, connection state and the most recent errors. Logs are kept for at most 30 days, so collect them while the problem is fresh. Also copy any browser-console error that appeared before the POS was able to write its own log entry.

## Details[​](#details "Detailsへの直接リンク")

* **Code:** `HOST131` (`RESPONSE_HEADERS_REJECTED`)
* **Severity:** error
* **Introduced in:** WCPOS 1.10.0