I'm using different versions of the Magento 1.* and Magento 2.*, and I'd like to know how to explain to my clients what are the impacts of the core files changed.

For example these bad points below, I know these are possible yet but with many time more:

  • No more updates.
  • No more security patches.
  • Third-party modules not working well.

Please tell me more points and official links.


Some major impacts of changing core files directly are listed below:

  • Making changes in core files directly makes it difficult to debug issues in functionality, since most of the Magento developers follow standard and think that there should not be any core files modified. So they do not go deeper into core Magento's files to debug issue.
  • If some core files have been modified, it can create conflict while applying security patches or upgrading Magento.

If you want to make changes in default functionality of Magento, then Magento has provided many ways to do so.

There are 3 basic ways to properly modify Magento code. Properly modifying simply means that we will not be changing any of the core files.

Override: create the exact same folder structure as the class you are trying to override in app/code/local/Mage. This file will be called instead of the one from the core folder.

Rewrite: redirect a specific core class to another class.

Observer: create a custom listener to handle events generated by the core.


The points which you have told are correct.

Changing codes in core files will create problems for next developer to find the changes.

The changes that are done in core files becomes sometimes messy when we want to revert back the changes.

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