X-Up-Fail-Mode

This request header contains the mode of the layer that Unpoly updates when the server sends an error response.

An error response has a status code other than 2xx, but still contains HTML.

Server-side code is free to render different HTML for different modes. For example, you might prefer to not render a site navigation for overlays.

Example

Assume we have the following form in a drawer overlay. The form targets the root layer:

<!-- label: Form within an overlay -->
<form action="/submit" up-submit up-layer="root"> <!-- mark: up-layer="root" -->
  ...
</form>

Because failed form submissions update the <form> element, submitting this form will send the following headers:

X-Up-Mode: root
X-Up-Fail-Mode: drawer