JIT is incompatible with third party extensions that override zend_execute_ex(). JIT disabled.

Description

The root cause is that PHP’s JIT has a fundamental incompatibility with extensions that override the engine’s core execution handler zend_execute_ex().

When such an extension is loaded, PHP proactively disables JIT and shows that warning.

This issue goes far beyond just debuggers and coverage tools. Any extension that instruments code, like profilers, APMs, and security modules, can trigger it.

  • Debuggers & Code Coverage: xdebug, pcov, xhprof, pinba, suhosin

  • Performance & APM Tools: blackfire, newrelic, tideways_xhprof, ddtrace, solarwinds

  • Security Modules: bt_security_notice, bt_safe, imunify360

  • Async & Server Frameworks swoole

  • PHP Internals & Testing (Zend DTrace, uopz (User Operations for Zend), Zend Observer API (older implementations))

  • Other APM & Instrumentation: skywalking

Note: the list above is not exhaustive.

Example

Solutions

  • Manage Development vs Production: for extensions that are meant for development, like xdebug and pcov, the simplest solution is to only load them in your development environment, such as by using different php.ini files.

  • Check for Alternative APIs or Versions: the newer Zend Observer API is the most JIT-friendly method for instrumenting code. Modern versions of tools like newrelic may support JIT by using this API, so always consult an extension’s latest documentation.

  • Consult Vendor Docs: many vendors provide specific JIT guidance. For instance, specific settings can be used to allow JIT to work with imunify360.

Changed Behavior

This error may appear following an evolution in behavior, in previous versions. See ` <https://php-changed-behaviors.readthedocs.io/en/latest/behavior/.html>`_.