Zend Guard Loader
When setting 'zend_loader.obfuscation_level_support' directive with levels 2 or 3, you might get a crash instead of standard PHP output. This happens only on specific code, which involves (as far as we tested) spl_autoload_register().
Fixed loaders are available here for the time being:
for Windows (PHP 5.5+5.6 - copy over installed Guard Loader):
for Linux and Mac (Including README and OPCache - 32/64 bit)
The final packages will be similar to those - for any feedback on the fixed binaries if you used them please open a support ticket for reporting.