WSOD while sending headers, probably Cache-related

Question

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 = $this->headers->allPreserveCaseWithoutCookies();
unset($headers['Cache-Control']);
unset($headers['Content-language']);
unset($headers['Date']);
unset($headers['X-Drupal-Dynamic-Cache']);
unset($headers['X-UA-Compatible']);
unset($headers['X-Content-Type-Options']);
unset($headers['Expires']);
unset($headers['Vary']);
foreach ($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

zend_extension=/usr/local/opt/php/lib/php/20180731/opcache.so

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

Answer 1

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.

Answer 2

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

to

http.response.debug_cacheability_headers: false

It's working again.