>>> [!note] Migrated issue <!-- Drupal.org comment --> <!-- Migrated from issue #3206178. --> Reported by: [gábor hojtsy](https://www.drupal.org/user/4166) >>> <h3 id="summary-problem-motivation">Problem/Motivation</h3> <p>Now that we have a Drupal 9 to 10 deprecation job running, I've been processing the results, and found that out of 5420 total projects, 1828 of them fail with this fatal error:</p> <blockquote><p>Fatal error: Cannot redeclare composerRequireDrupal9() (previously declared in /var/lib/drupalci/workspace/drupal-checkouts/drupal10/vendor/composer/autoload_real.php:72) in /var/lib/drupalci/workspace/drupal-checkouts/drupal12/vendor/composer/autoload_real.php on line 79</p></blockquote> <p>Top 50 projects that fail with this include the following:</p> <ul> <li>pathauto 1.x-dev</li> <li>entity_reference_revisions 1.x-dev</li> <li>inline_entity_form 1.x-dev</li> <li>google_analytics 3.x-dev</li> <li>twig_tweak 2.x-dev</li> <li>mailsystem 4.x-dev</li> <li>entity 1.x-dev</li> <li>linkit 5.x-dev</li> <li>honeypot 1.x-dev</li> <li>views_infinite_scroll 1.x-dev</li> <li>smtp 1.x-dev</li> <li>backup_migrate 5.0.x-dev</li> <li>colorbox 1.x-dev</li> <li>adminimal_theme 1.x-dev</li> <li>focal_point 1.x-dev</li> <li>config_split 1.x-dev</li> <li>eu_cookie_compliance 1.x-dev</li> </ul> <p>I tried scanning the code locally with Upgrade Status against pathauto and entity reference revisions and could not reproduce this problem. </p> <p>I also clustered the errors based on which drupalX thread they failed on, and all of them failed some. drupal1 to drupal32. Each thread had between 45-70 failed projects.</p> <h4 id="summary-steps-reproduce">Steps to reproduce</h4> <h3 id="summary-proposed-resolution">Proposed resolution</h3> <h3 id="summary-remaining-tasks">Remaining tasks</h3> <h3 id="summary-ui-changes">User interface changes</h3> <h3 id="summary-api-changes">API changes</h3> <h3 id="summary-data-model-changes">Data model changes</h3>