Migrate Mezzio applications from v2 to v3

1.3.0 2022-11-16 19:46 UTC


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🇷🇺 Русским гражданам

Мы, участники Laminas, родились и живем в разных странах. У многих из нас есть друзья, родственники и коллеги как в России, так и в Украине. Некоторые из нас родились в России. Некоторые из нас живут в России. У некоторых бабушки и дедушки сражались с фашистами во Второй мировой войне. Здесь никто не поддерживает фашизм.

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You trust us enough to use our software. We ask that you trust us to say the truth on this. We need your help. Go out and protest this unnecessary war. Stop the bloodshed. Say "stop the war!"

This library provides a tool for migrating from Mezzio v2 to v3.


Run the following to install this library:

$ composer require --dev mezzio/mezzio-migration


Once you have installed the tool, execute it with the following:

$ ./vendor/bin/mezzio-migration migrate

Cloning versus composer installation

If you'd rather clone the tooling once and re-use it many times, you can do that instead. Clone using:

$ git clone

And then, instead of using ./vendor/bin/mezzio-migration migrate, use /full/path/to/mezzio-migration/bin/mezzio-migration.


Our goal is to prepare a downloadable phar file that can be installed in your system and re-used; this change will come at a future date.


All external packages used within your project must be compatible with Mezzio v3 libraries. If you are unsure, check their dependencies.

This script will uninstall all dependent packages and then will try to install them with the latest compatible version. In case any package is not compatible, the script will report an error indicating which package need to be updated.

The following table indicates Mezzio package versions compatible with version 3, and to which the migration tool will update.

What does the tool do?

In order to operate, the tool requires that the application directory contains a composer.json file, and that this file is writable by the script.

Next, it attempts to detect the currently used Mezzio version. If the version detected is not a 2.X version, the script will exit without performing any changes.

It then performs the following steps:

  1. Removes the vendor directory.

  2. Installs current dependencies using composer install.

  3. Analyzes composer.lock to identify all packages which depends on Mezzio packages.

  4. Removes all installed Mezzio packages and packages that depend on them.

  5. Updates all remaining packages using composer update.

  6. Requires all Mezzio packages previously installed, adding the packages laminas/laminas-component-installer and mezzio/mezzio-tooling as development packages if they were not previously installed.

  7. Requires all packages installed previously that were dependent on Mezzio. This step may fail in situations where external packages are not yet compatible with Mezzio v3 or its required libraries.

  8. Updates config/pipeline.php:

    1. adds strict type declarations to the top of the file;
    2. adds a function wrapper (as is done in the version 3 skeleton);
    3. updates the following middleware:
      • pipeRoutingMiddleware becomes a pipe() statement referencing Mezzio\Router\Middleware\RouteMiddleware.
      • pipeDispatchMiddleware becomes a pipe() statement referencing Mezzio\Router\Middleware\DispatchMiddleware,
      • References to Mezzio\Middleware\NotFoundHandler become Mezzio\Handler\NotFoundHandler,
      • References to Mezzio\Middleware\ImplicitHeadMiddleware become Mezzio\Router\Middleware\ImplicitHeadMiddleware,
      • References to Mezzio\Middleware\ImplicitOptionsMiddleware become Mezzio\Router\Middleware\ImplicitOptionsMiddleware,
    4. pipes Mezzio\Router\Middleware\MethodNotAllowedMiddleware after Implicit*Middleware (or if these are not piped, after Mezzio\Router\Middleware\RouteMiddleware).
  9. Updates config/routes.php:

    1. adds strict type declaration on top of the file;
    2. adds a function wrapper (as is done in the version 3 skeleton).
  10. Replaces public/index.php with the latest version from the v3 skeleton.

  11. Updates container configuration if pimple or Aura.Di were used (config/container.php) from the latest skeleton version. Additionally, it does the following:

    • For pimple: the package xtreamwayz/pimple-container-interop is replaced by laminas/laminas-pimple-config.
    • For Aura.Di: the package aura/di is replaced by laminas/laminas-auradi-config.
  12. Migrates http-interop middleware to PSR-15 middleware using ./vendor/bin/mezzio migrate:interop-middleware.

  13. Migrates PSR-15 middleware to PSR-15 request handlers using ./vendor/bin/mezzio migrate:middleware-to-request-handler.

  14. Runs ./vendor/bin/phpcbf if it is available.

What should you do after migration?

You will need to update your tests to use PSR-15 middleware instead of http-interop middleware. This step is not done automatically because it is too complicated. We can easily change imported classes, but unfortunately test strategies and mocking strategies vary widely, and detecting all http-interop variants makes this even more difficult.

Please manually compare and verify all changes made. It is possible that in some edge cases, the script will not work correctly. This will depend primarily on the number of modifications you have made to the original skeleton.

Configuration-driven pipelines and routes

The script does not work currently make any modifications to pipeline and route configuration; these will need to be updated manually.