OPcache preloading broken in v1.12.0 — hangs on startup / undefined constant errors #2255
Description
What happened?
After upgrading to FrankenPHP v1.12.0, OPcache preloading no longer works. v1.11.2 works fine with the same configuration.
We observe two different failure modes depending on environment:
On ARM64 (AWS ECS, Debian): Every request returns a fatal error — a core PHP constant is undefined:
PHP Fatal error: Uncaught Error: Undefined constant "PHP_VERSION_ID" in /app/vendor/autoload.php:5
Stack trace:
#0 /app/public/index.php(22): require()
#1 {main}
On ARM64 (Docker Desktop for macOS): FrankenPHP hangs indefinitely during startup. The Caddy admin endpoint starts, TLS/HTTPS is configured, but the server never reaches the "FrankenPHP started" / "server running" state. No error is logged — it simply deadlocks.
Disabling opcache.preload resolves both issues immediately.
How to reproduce
- Use the
dunglas/frankenphp:1.12.0-php8.5Docker image - Enable OPcache preloading:
opcache.ini:
opcache.preload = /app/preload.php
opcache.preload_user = www-datapreload.php:
<?php
require_once __DIR__ . '/vendor/autoload.php';- Start FrankenPHP — it either hangs during startup or serves fatal errors on every request.
Environment
- FrankenPHP: v1.12.0
- PHP: 8.5.3 (ZTS)
- Caddy: v2.11.2
- Docker image:
dunglas/frankenphp:1.12.0-php8.5@sha256:7b54e661c5be17c5ace0efeec6b41f612509ea75028c0b72269f9ba8491431da - Caddyfile: Using
php_serverdirective (classic mode, not worker mode) - Tested on ARM64 (both Docker Desktop macOS and AWS ECS)
Working version
v1.11.2 with the same preload configuration works correctly:
dunglas/frankenphp:1-php8.5@sha256:7345f3393d108ba205c20240110f3688c20489b6a2caaf5bca3e99039f016aab
Additional context
- This may be related to the "sandboxed environment moved to C side" change in v1.12.0.
- Similar to Uncaught Error: Call to undefined function dirname() #685 where
dirname()became undefined due to OPcache preloading corruption.