TYPO3 Extension Upgrade Skill

Systematic framework for upgrading TYPO3 extensions to newer LTS versions. Extension code only -- NOT for project/core upgrades.

Upgrade Toolkit

Tool	Purpose	Files
Extension Scanner	Diagnose deprecated APIs	TYPO3 Backend
Rector	Automated PHP migrations	.php
Fractor	Non-PHP migrations	FlexForms, TypoScript, YAML, Fluid
PHPStan	Static analysis	.php

Core Workflow

1. Complete planning phase (consult references/pre-upgrade.md)
2. Create feature branch (verify git is clean)
3. Update composer.json constraints for target version
4. Audit third-party dependencies for major version changes (consult references/third-party-dependency-upgrades.md)
5. Run rector process --dry-run then review and apply
6. Run fractor process --dry-run then review and apply
7. Run php-cs-fixer fix
8. Run phpstan analyse against each supported dependency version and fix errors
9. Run phpunit and fix tests
10. Test in target TYPO3 version(s)
11. Verify success criteria (consult references/verification.md)

When NOT to Apply Automatically

Do NOT blindly apply Rector/Fractor if dual-version compatibility is needed, tests are missing, changes are unclear, or complex APIs (DBAL, Extbase) are affected. Instead: apply specific rules manually, test between each change.

Third-Party Dependency Upgrades

When composer.json widens constraints to a new major version: enumerate API usages, cross-reference the new version's API, flag interface/concrete-only methods, verify mocks against all supported versions, use adapter pattern for signature differences, run PHPStan against each major version. See references/third-party-dependency-upgrades.md.

Quick Commands

rector process --dry-run && rector process        # PHP migrations
fractor process --dry-run && fractor process       # Non-PHP migrations
php-cs-fixer fix && phpstan analyse && phpunit     # Quality checks

Asset Templates

Config templates in assets/: rector.php, fractor.php, phpstan.neon, phpunit.xml, .php-cs-fixer.php

References

Reference	Use when...
references/pre-upgrade.md	Starting an upgrade: planning checklist, version audit, risk assessment
references/api-changes.md	Checking deprecated/removed APIs by TYPO3 version
references/api-traps.md	Cross-version footguns: TCA restrictions, boot order, DI bypass
references/upgrade-v11-to-v12.md	Upgrading from TYPO3 v11 to v12
references/upgrade-v12-to-v13.md	Upgrading from TYPO3 v12 to v13
references/upgrade-v13-to-v14.md	Upgrading from TYPO3 v13 to v14
references/dual-compatibility.md	Maintaining dual compatibility (v12 + v13)
references/real-world-patterns.md	Looking for real-world migration examples
references/toolchain-output.md	Understanding Rector/Fractor dry-run output
references/troubleshooting.md	Rector broke code, PHPStan errors, test failures
references/third-party-dependency-upgrades.md	Upgrading non-TYPO3 dependencies (major version bumps, adapter patterns)
references/verification.md	Checking success criteria and real-world testing
references/multi-version-worktrees.md	Per-LTS worktree layout, backport workflow, cross-version CI matrix

External Resources

• TYPO3 Rector
• Fractor
• TYPO3 Core Changelog