Learn how to fix the “autoload error already defined” issue in Magento 2. Our Magento Support team is here to help you with your questions and concerns.

How to Fix Magento’s “Autoload Error Already Defined” Error

In Magento 2, running into the “autoload error already defined” error is a sign of an issue with how classes and modules are loaded in the system.

This error usually occurs when a class or module is defined in multiple locations. It causes Magento to get confused about which definition to use.

Let’s take a look at some of the common causes and fixes for this issue.

Causes Behind the Error

• We may have accidentally installed the same module twice, either manually or through Composer conflicts.
• Two different modules may have classes or components with the same name, leading to a clash.
• If we have placed code files (like .php files) containing class definitions outside of the designated Magento directory structure, they may conflict with existing definitions.

1. Identify Conflicting Modules

• Look for clues about the specific class or module causing the issue. Our Experts suggest paying attention to terms like “Module Name” or “Class Name”.
• Furthermore, use the grep command on the Magento installation directory to find all occurrences of the conflicting element. This will help pinpoint the duplicate definitions.

2. Address the Conflict

1. Duplicate Module:

   If we find the same module installed twice, try these:

   • Uninstall the manually installed version if we have it via Composer.
   • Or, if it was installed manually, remove the duplicate module directory manually.
   • Use Composer to resolve any dependency conflicts that may be causing the double installation.
2. Conflicting Module Names:

   Also, if two modules have the same class name, check if one module can use a different class name to avoid the conflict
3. Manual Code:

   If we place code outside the designated structure, we can move the code files to the locations within the Magento app directory structure. Alternatively, we can get the code to use plugins or extensions instead of directly modifying core Magento files.

3. Clear Cache and Recompile

After resolving the conflict, run the following commands to make sure Magento reloads with the updated configuration:

php bin/magento cache:flush
php bin/magento setup:di:compile

Let us know in the comments if you need further help with the error.

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Conclusion

In brief, our Support Experts demonstrated how to fix the “autoload error already defined” issue in Magento 2.