astrid-runtime/astrid · error

CORS origin has a trailing slash; remove it (browsers send…

Error message

CORS origin {raw:?} has a trailing slash; remove it (browsers send `Origin:` without one)

What it means

Validation guard in validate_cors_origin: the entry ends with a trailing slash, but browsers send Origin: without one and the response header is byte-matched, so 'https://app.example/' would silently never match; the entry is rejected with a pointed fix.

Solutions

1. Delete the trailing slash from the origin entry
2. Use the exact form the browser sends, e.g. https://app.example
3. Re-test preflight after the fix

When it happens

Trigger: Thrown at crates/astrid-gateway/src/config.rs:221 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of astrid-runtime/astrid@affd8760f4 (2026-09-09). Data as JSON: /api/errors/1f4565e0c43c6cf3. Report an issue: GitHub.

Appendix: source

Thrown at crates/astrid-gateway/src/config.rs:221

        anyhow::bail!(
            "CORS origin {raw:?} carries userinfo (user:password); browsers strip it before sending `Origin:` so this can never match"
        );
    }
    if parsed.path() != "" && parsed.path() != "/" {
        anyhow::bail!(
            "CORS origin {raw:?} carries a path ({:?}); origins are scheme+host+port only",
            parsed.path()
        );
    }
    if parsed.query().is_some() || parsed.fragment().is_some() {
        anyhow::bail!(
            "CORS origin {raw:?} carries a query/fragment; origins are scheme+host+port only"
        );
    }
    // Disallow trailing-slash forms — browsers send `https://app.example`
    // (no slash) in `Origin:` and the response header is byte-matched.
    if raw.ends_with('/') {
        anyhow::bail!(
            "CORS origin {raw:?} has a trailing slash; remove it (browsers send `Origin:` without one)"
        );
    }
    // Reject a raw IDN — browsers transmit the Punycode (ASCII)
    // form in `Origin:`, so the bytes wouldn't match anyway. The
    // `Url` parser already normalizes the host to its ASCII form on
    // parse; if the *raw* string contained a non-ASCII character,
    // the parsed `origin()` ASCII-serialization won't equal `raw`.
    let parsed_ascii = parsed.origin().ascii_serialization();
    if parsed_ascii != raw {
        anyhow::bail!(
            "CORS origin {raw:?} must be ASCII-only (Punycode); browsers send the Punycoded form in `Origin:`. Use {parsed_ascii:?} instead."
        );
    }
    Ok(())
}

#[cfg(test)]

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