I have a very strange problem with a fresh Drupal install: On some pages, I receive a WSOD with ERR_EMPTY_RESPONSE:


It happens for instance when on admin/config/development/performance I click Clear all caches. (But also other pages are affected – for instance the Layout Builder page of a Node type.)

Interestingly, I could isolate the bug down here: If in vendor/symfony/http-foundation/Response.php::sendHeaders() I tweak the code so that it unsets a lot of the headers to be sent (actually, all of them but X-Generator and X-Frame-Options), the error disappears.

$headers = $this->headers->allPreserveCaseWithoutCookies();
foreach ($headers as $name => $values) {

Based on the headers I unset, it seems that it is a caching-related problem. (However, Caching is switched off, Browser and proxy cache maximum age is set to <no caching>.)

My setup:

  • installed Drupal 8.7.5 via composer
  • on my local machine, a MacBook Pro with macOS High Sierra
  • installed via Homebrew
    • PHP 7.3
    • Apache 2.4
    • MySQL 5.7.24

Any idea what the problem might be?

Edit: Regarding Apache error logs: I first had no entries there but now I debugged again and saw such one:

[core:notice] [pid 92592] AH00052: child pid 98466 exit signal Bus error (10)

Googling gave the suggestion to apc_clear_cache(); but it's not available in PHP7. So I ran opcache-reset().

Result: Problem is still there, now already when opening the page admin/config/development/performance.

Now the error logs say:

 [core:notice] [pid 7428] AH00052: child pid 7446 exit signal Segmentation fault

Google suggests this is likely caused by a syntax error in php.ini or some included extension there. Thus I have taken out all extensions, including


but the problem remains.

Edit 2: Here's the output of my php -i (It uses the same php.ini file as phpinfo() in localhost). https://pastebin.com/ppvCpPA6

  • 1
    This might be easier to debug if you find the error log of the Apache instance you've installed via Homebrew and post the error message.
    – 4uk4
    Aug 9, 2019 at 9:39
  • 1
    Wouldn't it be better to have OPcache disabled completely when developing locally?
    – leymannx
    Aug 9, 2019 at 11:34
  • 1
    Thanks, just disabled it with opcache.enable=0 in php.ini, problem remains. Aug 9, 2019 at 11:47
  • 1
    Be sure that your /usr/local/etc/php/7.3/conf.d/ext-opcache.ini doesn't override your php.ini, see stackoverflow.com/q/27640772/2199525.
    – leymannx
    Aug 9, 2019 at 12:12
  • 1
    Yes, I'm sure, it only contains this commented out line: ;zend_extension=/usr/local/opt/php/lib/php/20180731/opcache.so Aug 9, 2019 at 12:21

2 Answers 2


Now I could solve it myself. My Apache error logs did show

AH00052: child pid 7363 exit signal Segmentation fault (11)

so it must have been a problem with the Apache config.

I took the opportunity to reinstall Apache and configure it with FCGI/FPM according to this and now the problem is gone.

  • 1
    Hurray!!!!!! :)
    – leymannx
    Aug 15, 2019 at 15:50

I have same issue with set debug mode when run

drupal smo dev

Problem will gone If I set to prod mode

 drupal smo prod

After sometime debug I found problem because cache tag header. And I change

http.response.debug_cacheability_headers: true


http.response.debug_cacheability_headers: false

It's working again.

  • 1
    Didn't know what smo meant. Where exactly did you change these tags?
    – leymannx
    Aug 9, 2019 at 11:38
  • @Jonh: Thanks, drupal smo prod gave me PHP Fatal error: Declaration of Drupal\Component\DependencyInjection\Container::set($id, $service) must be compatible with Symfony\Component\DependencyInjection\ContainerInterface::set($id, $service, $scope = self::SCOPE_CONTAINER) in /Users/jorge/data/my/code/test/d8/web/core/lib/Drupal/Component/DependencyInjection/Container.php on line 49 Aug 9, 2019 at 12:05
  • 1
    @leymannx Grepping gave me core/core.services.yml – but my value is already false there. Aug 9, 2019 at 12:06
  • @GeorgJähnig, the initial value in core.service.yml can be overwritten in /sites/default/services.yml or /sites/development.services.yml, the 2nd one only when enabled in settings.php, which is usually the case for dev modes, see drupal.stackexchange.com/questions/251768/…
    – 4uk4
    Aug 9, 2019 at 13:02
  • @4k4 OK, thanks! I have no sites/default/services.yml file (nor development.services.yml), and even the default.services.yml (which I guess has no effect) has only a http.response.debug_cacheability_headers: false line. Aug 9, 2019 at 21:47

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