Missing Csrf token cookie - cakephp

Question

I'm relatively new to CakePHP (v3.7). I have an application in which I'm getting a "Missing Csrf Token Cookie" error.
In Application.php, I have:
$options = []; // I'm fine with the default options.
$csrf = new CsrfProtectionMiddleware($options);
$middlewareQueue->add($csrf);
The form page has a hidden form element with the _csrfToken in it.
I'm confused as to why it's not being found on the POST?
Digging further, I found that in CsrfProtectionMiddleware.php, the _validateToken() function below behaves as follows:
$cookies is null (there are no cookies set.)
thus, $cookie is null.
$post actually contains the content of the _csrfToken parameter from the hidden parameter on the page. However the function never looks at it. Because $cookie is null,
the if(!$cookie) statement causes an InvalidCsrfTokenException to be thrown.
protected function _validateToken(ServerRequest $request)
{
$cookies = $request->getCookieParams();
$cookie = Hash::get($cookies, $this->_config['cookieName']);
$post = Hash::get($request->getParsedBody(), $this->_config['field']);
$header = $request->getHeaderLine('X-CSRF-Token');
if (!$cookie) {
throw new InvalidCsrfTokenException(__d('cake', 'Missing CSRF token cookie'));
}
if (!Security::constantEquals($post, $cookie) && !Security::constantEquals($header, $cookie)) {
throw new InvalidCsrfTokenException(__d('cake', 'CSRF token mismatch.'));
}
}
}
Obviously, the middleware is expecting an actual cookie, in addition to a hidden parameter. Where is this cookie set (or supposed to be set?)
Update:
I checked on the browser side. The cookie is being set, but the browser isn't returning it on the POST request.
Here's CakePHP's RESPONSE to the original GET request to populate the page:
Connection: Keep-Alive
Content-Length: 3013
Content-Type: text/html; charset=UTF-8
Date: Wed, 08 May 2019 23:07:31 GMT
Keep-Alive: timeout=5, max=100
Server: Apache/2.4.33 (Unix) PHP/7.1.1
Set-Cookie: csrfToken=b553dd2e06e57f6d514ee41a120e1c60084adafddfbaa6f72db1f7f590fcf50143876ac817d29d6f1cf9a786031d6235ba21e265b9d3b2a0ee4535854f048b66; path=/webroot/
X-Powered-By: PHP/7.1.1
Note the csrfToken cookie.
... and here's the POST that the browser sends back with the form data
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
Cache-Control: no-cache
Connection: keep-alive
Content-Length: 184
Content-Type: application/x-www-form-urlencoded
DNT: 1
Host: *************
Origin: ****************
Pragma: no-cache
Referer: ***************
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.131 Safari/537.36
Query String Parameters
redirect: /Users/login
Form Data
_method: POST
_csrfToken: b553dd2e06e57f6d514ee41a120e1c60084adafddfbaa6f72db1f7f590fcf50143876ac817d29d6f1cf9a786031d6235ba21e265b9d3b2a0ee4535854f048b66
username: xxxxxxxxxx
password: xxxxxxxxxx
Note that it's sending back the hidden form parameter _csrfToken, but NOT the cookie.
Thanks for any help...

Answer 1

This turned out to be a problem with the DOCUMENT_ROOT directory setting in Apache. It was set to the parent directory of webroot, instead of to webroot itself. When I changed it everything worked.