Some drush commands fail; Some Drupal pages are blank.
The failing drush commands report "Segmentation fault: 11"
The Apache log (e.g. php-error.log in MAMP) also shows the same error.
If you use a gulp or grunt workflow - to compile your theme's SASS etc. - you may run into a problem where drush commands throw a segmentation fault 11 as does Apache whilst serving Drupal pages as blanks (WSDs).
This is because files from your
gulp workflow environment in
node_modules are erroneously being registered by Drupal itself as a bi-product of
drush cache-clear all for example. There are dozens of these .js files and Drupal can't handle them ... it's possibly a PCRE regex that is the root cause as this is known elsewhere. Anyway ...
It doesn't always happen
It's not clear whether some modules (like Browser Sync for example) induce this error as a node.js style (i.e. gulp or grunt) workflow can work perfectly before failing in this way.