Upgrade instructions to Drupal 9 for existing projects

[andeersg]

I'm trying to upgrade to Drupal 9.0.0-rc1. But I run into errors such as:

- Installation request for symfony-cmf/routing (locked at 1.4.1) -> satisfiable by symfony-cmf/routing[1.4.1].

Should all these packages be required at 9.0.0-rc1?

"drupal/core": "^8.8.0",
"drupal/core-composer-scaffold": "^8.8.0",
"drupal/core-dev": "^8.8.0"

Or is that the wrong approach? Could be a nice instruction to have in the readme maybe.

[geerlingguy]

FYI, I've had this issue as well on my live stream: https://github.com/geerlingguy/drupal-for-kubernetes/issues/29

[andeersg]

I think I figured something out. I followed https://www.drupal.org/docs/upgrading-drupal/upgrading-from-drupal-8-to-drupal-9-or-higher, but had to add drupal/core:

composer require drupal/core-recommended:^9.0.0 drupal/core-composer-scaffold:^9.0.0 drupal/core:^9.0.0  --update-with-dependencies --no-update

composer require drupal/core-dev:^9.0.0 --dev --update-with-dependencies --no-update

composer update

Then it upgraded without errors. But maybe drupal/core should be removed now that drupal/core-recommended is present?

[andeersg]

Removing drupal/core seems to work.

[lchabrand]

Hi, did you find the best solution ?

[andeersg]

What seems to work is:

composer require drupal/core-recommended:^9.0.0 drupal/core-composer-scaffold:^9.0.0 drupal/core:^9.0.0  --update-with-dependencies --no-update

composer require drupal/core-dev:^9.0.0 --dev --update-with-dependencies --no-update

composer update

composer remove drupal/core

Only tested locally, but that seems to work fine. And keeps all the good parts of this project :)