symfony/process · error · BadMethodCallException

Cannot serialize…

Error message

Cannot serialize Symfony\Component\Process\Pipes\WindowsPipes

What it means

WindowsPipes manages temporary files and open handles used for process I/O on Windows; these OS-level resources cannot be serialized. __serialize() deliberately throws BadMethodCallException to prevent it.

Solutions

Close/finish the process before persisting anything
Persist only serializable configuration and rebuild the Process on demand
Exclude the Process/pipes property from your object's __serialize()/__sleep()

Example fix

// before
public function __serialize(): array { return ['process' => $this->process]; }
// after
public function __serialize(): array { return ['command' => $this->process->getCommandLine()]; }

Defensive patterns

Strategy: type-guard

Validate before calling

if ($process->isRunning()) { throw new \LogicException('Cannot persist a running process'); }

Type guard

function isSerializable(mixed $v): bool { try { serialize($v); return true; } catch (\Throwable) { return false; } }

Try / catch

try { $data = serialize($obj); } catch (\BadMethodCallException $e) { $data = serialize($obj->toDescriptor()); }

Prevention

Exclude Process/pipes properties from serializable wrappers
Cache process descriptors, not objects
Test cache paths on Windows where pipes use temp files

When it happens

Trigger: serialize($process->getProcessPipes()) or serializing any object graph containing a live WindowsPipes instance (e.g. a running Process stored in cache/session).

Common situations: Caching a running Process on a Windows host, queueing a live Process object, or serialize-based debug logging.

Understand the failure class

Background: "JSON serialization failed", "not JSON serializable", "Failed to serialize": why JSON marshaling errors happen and how to fix them — this error's family across 46 libraries.

Related errors

AI-assisted analysis of symfony/process@99b85026db (2026-09-14). Data as JSON: /api/errors/4e5884c5cd653d42. Report an issue: GitHub.

Appendix: source

Thrown at Pipes/WindowsPipes.php:92

                        flock($this->lockHandles[$pipe], \LOCK_UN);
                        fclose($this->lockHandles[$pipe]);
                        unset($this->lockHandles[$pipe]);
                        continue 2;
                    }
                    $this->fileHandles[$pipe] = $h;
                    $this->files[$pipe] = $file;
                }
                break;
            }
            restore_error_handler();
        }

        parent::__construct($input);
    }

    public function __serialize(): array
    {
        throw new \BadMethodCallException('Cannot serialize '.__CLASS__);
    }

    public function __unserialize(array $data): void
    {
        throw new \BadMethodCallException('Cannot unserialize '.__CLASS__);
    }

    public function __destruct()
    {
        $this->close();
    }

    public function getDescriptors(): array
    {
        if (!$this->haveReadSupport) {
            $nullstream = fopen('NUL', 'c');

            return [

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