I'm working on a solution that requires adding a bit of functionality to the magento installation process. How do I override a file in root/setup/src/Magento/...

How would i override setup/src/Magento/Setup/Model/Installer.php?

1 Answer 1


I am not sure you can do this in Magento directly. But composer may be of some assistance.

"autoload": {
    "files": [
    "exclude-from-classmap": [

The files array tells composer to load those files first. The exclude-from-classmap array tells composer to not load the file at all. So don't load the core file, copy it somewhere, make your modifications, and load your new file.

  • I've done what you stated, issued a composer update, and confirmed my file is being loaded... But breakpoints still fire on the original file.
    – CarComp
    Jan 10, 2020 at 15:55
  • try composer dumpautoload command to make sure composer flushed its autoloader completely. If this doesn't help, try composer update --lock to make sure the changes where updated in the project state.
    – wesleywmd
    Jan 11, 2020 at 21:08

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