Error when trying to install TYPO3 8.7 with php 7.2 using composer 2

[rowild]

I need to fix an old TYPO3 8.7 php 7.4 installation, which broke due to a server update. So I am trying to recreate it locally with ddev, but when starting

ddev composer require typo3/cms-base-distribution:^8.7

I do get this error:

typo3/cms-composer-installers contains a Composer plugin which is currently not in your allow-plugins config. See https://getcomposer.org/allow-plugins
Do you trust "typo3/cms-composer-installers" to execute code and wish to enable it now? (writes "allow-plugins" to composer.json) [y,n,d,?] y
  - Installing typo3/cms-composer-installers (v1.5.10): Extracting archive
PHP Fatal error:  Declaration of TYPO3\CMS\Composer\Installer\Downloader\T3xDownloader2::extract(Composer\Package\PackageInterface $package, $file, $path) must be compatible with Composer\Downloader\ArchiveDownloader::extract(Composer\Package\PackageInterface $package, string $file, string $path): React\Promise\PromiseInterface in /var/www/html/vendor/typo3/cms-composer-installers/src/Installer/Downloader/T3xDownloader2.php on line 27
Composer [require typo3/cms-base-distribution:^8.7] failed, composer command failed: exit status 255. stderr=

I have no idea, how to fix this problem. What am I doing wrong?

[rowild]

As it happens to very often, 5 minutes after asking I find the answer myself. Here it is for those, who happen to be in the same situation:

Downgrade to composer 1. Do so in the config.yaml changing the following line ti this:

composer_version: "1"

Try running ddev composer ... , and if ddev is not downgrading to composer 1, then do so yourself directly in your ddev instance:

ddev ssh
composer self-update 1.10.26

That should get the install process in gear...

[stasadev]

Try Composer 2.2 LTS

ddev config --composer-version=2.2
ddev restart
ddev composer -V

Composer version 2.2.25 2024-12-11 11:58:02

Composer v1 is already EOL, it seems very slow after using v2, and the metadata for v1 will be shut down soon (August 1st, 2025).
https://blog.packagist.com/shutting-down-packagist-org-support-for-composer-1-x/

[rowild]

I know that it's out of date, but as written above there is a typo3 composer plugin that is simply not available for composer 2. Therefore the downgrade.

[stasadev]

Have you tried it? I wouldn’t recommend 2.2 LTS if I hadn't tested it myself. Composer 2.8.x really doesn’t work, but 2.2 LTS does.

[rowild]

Ah, 2.2 LTS - no, I haven't tried that one, sorry! Will do! Thanks!

[stasadev]

More context about Composer 2.2 LTS composer/composer#10340