When using JSON API Extras' ability to change the base path, 4xx errors returned for using an invalid field in filter or sort returns HTML response rather than JSON

Yes, I'm passing in both Accept and Content-type with that value.

I'm sending

Accept: application/vnd.api+json
Content-type: application/vnd.api+json

I am also getting HTML for 404s.

Running docksal locally with latest D8. Let me know if there's something else I can test/report for you.

I will test as soon as possible (tomorrow, most likely).

I was able to test this issue on a Platform.sh server and I am getting the same response that I originally reported. After I test the patch, I will PM you a live endpoint you can test against.

This is the output after running the test in the patched file:

Testing Drupal\Tests\jsonapi\Functional\NodeTest F.....F. 8 / 8 (100%)

Time: 4.65 minutes, Memory: 8.00MB

There were 2 failures:

1) Drupal\Tests\jsonapi\Functional\NodeTest::testPatchPath
Failed asserting that Array &0 (
'errors' => Array &1 (
0 => Array &2 (
'code' => 0
'detail' => 'The current user is not allowed to PATCH the selected field (path).'
'id' => '/node--camelids/91ca3c86-f390-46a3-88d8-9dc5fa2ecb76'
'links' => Array &3 (
'info' => 'http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.4.4'
)
'source' => Array &4 (
'pointer' => '/data/attributes/path'
)
'status' => 403
'title' => 'Forbidden'
)
)
) is identical to Array &0 (
'errors' => Array &1 (
0 => Array &2 (
'code' => 0
'detail' => 'The current user is not allowed to PATCH the selected field (path). The following permissions are required: 'create url aliases' OR 'administer url aliases'.'
'id' => '/node--camelids/91ca3c86-f390-46a3-88d8-9dc5fa2ecb76'
'links' => Array &3 (
'info' => 'http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.4.4'
)
'source' => Array &4 (
'pointer' => '/data/attributes/path'
)
'status' => 403
'title' => 'Forbidden'
)
)
).

/var/www/docroot/modules/contrib/jsonapi/tests/src/Functional/ResourceTestBase.php:598
/var/www/docroot/modules/contrib/jsonapi/tests/src/Functional/ResourceTestBase.php:550
/var/www/docroot/modules/contrib/jsonapi/tests/src/Functional/NodeTest.php:283

2) Drupal\Tests\jsonapi\Functional\NodeTest::testPatchIndividual
Failed asserting that Array &0 (
'errors' => Array &1 (
0 => Array &2 (
'code' => 0
'detail' => 'The current user is not allowed to PATCH the selected field (created).'
'id' => '/node--camelids/403c8e56-4d7c-4332-9cc0-a70668f2eaba'
'links' => Array &3 (
'info' => 'http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.4.4'
)
'source' => Array &4 (
'pointer' => '/data/attributes/created'
)
'status' => 403
'title' => 'Forbidden'
)
)
) is identical to Array &0 (
'errors' => Array &1 (
0 => Array &2 (
'code' => 0
'detail' => 'The current user is not allowed to PATCH the selected field (created). The 'administer nodes' permission is required.'
'id' => '/node--camelids/403c8e56-4d7c-4332-9cc0-a70668f2eaba'
'links' => Array &3 (
'info' => 'http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.4.4'
)
'source' => Array &4 (
'pointer' => '/data/attributes/created'
)
'status' => 403
'title' => 'Forbidden'
)
)
).

/var/www/docroot/modules/contrib/jsonapi/tests/src/Functional/ResourceTestBase.php:598
/var/www/docroot/modules/contrib/jsonapi/tests/src/Functional/ResourceTestBase.php:550
/var/www/docroot/modules/contrib/jsonapi/tests/src/Functional/ResourceTestBase.php:1704

FAILURES!
Tests: 8, Assertions: 334, Failures: 2.

edit: disregard this comment. i'll report back shortly.

it is actually working on a fresh install using a node endpoint. let me try to find the root of the problem.

@e0ipso, I know; I am and have been. I just did that without thinking for a minute..

It is working fine on a fresh 8.5.3 install. So, as you expected, it must be stemming from something on my site, but I have no idea what just yet. I will try to find out and report back. It happens there for node and all other entity endpoint as well still.

I can confirm this is stemming from JSON API Extras. If I disable that module on the affected environment, I get a proper JSON response. Once I re-enable JSON API Extras, hitting an overridden endpoint with a non-existent field as a filter or sort results in an HTML response.

Here is a before and after

Seems to happen only if the "path prefix" is changed.

Given that, maybe it's still related to JSON API, and not the "extras" module.