Headers ( in netlify.toml and/or _headers ) not being applied

Support
1

I have some sites where the custom headers have seemed to stopped working. Some use the _headers approach and others use the [[headers]]] approach in the .toml.

I’ve created a simple Sveltekit site that has a basic build w/ the [[headers]] test applied, and it is not outputting the headers.

Here’s the test url: https://netlify-header-testing.netlify.app/

Here’s the .toml

[build]
	base = "/"
	publish = "build"
	command = "npm run build"

[build.environment]
	"NETLIFY_BUILD_DEBUG" = "true"

[[headers]]
	for = "/*"
	[headers.values]
		X-Content-Type-Options = "nosniff"
		X-Xss-Protection = "1; mode=block"
2

SvelteKit runs on Netlify Functions of Edge Functions. These headers don’t apply there. You’d have to add headers from within your SvelteKit code.