How to fix autoload error, Manual installation vs Magento composer installation

Autoload errors can occur when the same module or a shared package is installed twice using different methods (Composer vs. manual).

Since 1.16.0, paid WeltPixel extensions and themes install and update via Composer only. The manual (app/code) scenarios below apply to legacy installs made before 1.16.0. Composer access is under My Products at account.weltpixel.com.

When this happens

• Installing a WeltPixel extension via Magento Marketplace (Composer) (under vendor/weltpixel) and updating the same extension manually (under app/code/WeltPixel) causes an autoload error because the module is defined twice.

• Installing one WeltPixel extension via Marketplace (Composer) and a second one manually via weltpixel.com can also cause conflicts when both rely on a shared dependency (e.g., the “Backend” dependency pack) that ends up in two locations:
• • app/code/WeltPixel/Backend
  • vendor/weltpixel/m2-weltpixel-backend

Solution

Remove the duplicate so that only one copy remains installed:

1. Keep Composer install; remove manual copy
2. • Delete the manual version under: app/code/WeltPixel/<ExtensionName>

2. Keep manual install; remove Composer copy (legacy, pre-1.16.0 only; paid extensions now update via Composer, so option 1 is recommended)
3. • Remove the Composer version under: vendor/weltpixel/<extensionname>

After removing the duplicate, run your typical maintenance commands (e.g., php bin/magento setup:upgrade, recompile, deploy static content, and clear caches) to finalize the fix.

How to uninstall (manual vs. Composer)

For detailed uninstall instructions for both methods, see:
How to uninstall and remove a Magento 2 extension (manual vs composer)

Updated on: 28/09/2026