.How do I fix composer dependency conflicts during a Shopware 6 upgrade?
Most Common Cause
Most Shopware 6 upgrade conflicts happen because one or more plugins
still require older Symfony, Composer, or Shopware package versions. Disable or remove incompatible extensions
first, then run composer update again with the exact Shopware version constraint you want to install.
Quick Diagnostic — check these first
Rules out: outdated third-party extensions blocking the upgrade
Rules out: Shopware package requirements failing silently
Rules out: chasing secondary dependency errors instead of the root conflict
Rules out: manually pinned Symfony or Shopware packages
Cause 1 Incompatible plugins
Older plugins often lock Symfony, Doctrine, or Shopware core versions that no longer match the target release.
Fix: Disable all third-party plugins first, remove abandoned packages from composer.json, then upgrade plugins one by one after the Shopware core update succeeds.
Cause 2 Wrong PHP version
Composer checks PHP compatibility before installing packages. Even a minor version mismatch can block the entire upgrade.
Fix: Confirm your Shopware target version supports your installed PHP version. Update PHP first if needed, then clear Composer cache and rerun the update command.
Cause 3 Locked package versions
Many stores pin exact package versions in composer.json during older customisations. That blocks Composer from resolving newer dependency trees.
Fix: Remove hardcoded package versions where possible and
use Shopware’s recommended constraints. Then run the update with the --with-all-dependencies flag.
composer update --with-all-dependenciesCause 4 Corrupted Composer cache or lock file
Failed upgrade attempts sometimes leave stale package metadata or partial dependency states behind.
Fix: Clear the Composer cache, remove the vendor directory if needed, and regenerate dependencies from a clean state before retrying the upgrade.
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