Fatal error: UpstreamRequireCommand::configure() signature incompatible with Composer RequireCommand::configure(): void

[laetus007]

Summary

Running composer upstream:update-dependencies triggers a fatal error: Declaration of
PantheonSystems\UpstreamManagement\Command\UpstreamRequireCommand::configure() must be compatible with Composer\Command\RequireCommand::configure(): void. The codebase fails to load the upstream-management command class.

Steps to reproduce

1. Checkout repository and update dependencies (environment where Composer\RequireCommand defines configure(): void).
2. Run composer update:upstream-dependencies
3. Observe the fatal PHP error during bootstrap.

Error

PHP fatal error: PHP Fatal error: Declaration of PantheonSystems\UpstreamManagement\Command\UpstreamRequireCommand::configure() must be compatible with Composer\Command\RequireCommand::configure(): void in vendor/pantheon-systems/upstream-management/src/Command/UpstreamRequireCommand.php

Environment

PHP: 8.3.27
Terminus: 4.1.0 (observed user-agent)
Composer - version 2.9.2 2025-11-19

File: vendor/pantheon-systems/upstream-management/src/Command/UpstreamRequireCommand.php

Occurs when Composer uses a Composer version whose RequireCommand::configure() signature includes a return type of : void.

Expected behavior

The package should be compatible with the Composer version in use and not cause a fatal type/signature mismatch on class load.

Suspected cause

• Method signature mismatch between parent Composer\Command\RequireCommand::configure(): void and child UpstreamRequireCommand::configure() (missing or mismatched return type or visibility).
• Package does not constrain supported Composer versions or has not been updated to match Composer's method signature changes.

I've added :void to the method locally and am able to proceed at this time.

[tirazel]

We are running in to the same issue, and are using the local signature fix suggested above.

[kreynen-du]

Same issue with PHP version 8.3.30 and Composer version 2.9.5.

Adding :void worked for me too. Thanks @laetus007!

[kreynen]

While https://docs.cweagans.net/composer-patches/usage/defining-patches/ still discourages the use of dynamic .patch files, I created a PR for this fix so I could add .patch to #23 and include that in our Upstream. While limiting the version of Composer to ~2.7 at the project level is another way to fix this, it made more sense to get this into our projects so we could use composer upstream-required. Hope this helps someone else stay productive until a fix is in the release.

"patches": {
            "pantheon-systems/upstream-management": {
                "Fixes Fatal error: UpstreamRequireCommand::configure()": "https://patch-diff.githubusercontent.com/raw/pantheon-systems/upstream-management/pull/23.patch"
            }        
        },