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Today, I was dealing with the following error message on one of our Magento2 production environment.

After spending 2 hours trying to find the source of the problem in our custom modules, I was able to fix the issue by disabling the core module Magento_SampleData.

What is this module for? This module gives you different sample data ( CMS, Catalog, Customers ) which is useful during development and testing phase. For your production environment it is not necessary and also not recommended to have it installed, as you can read here.

Reset Administrator User Password in Magento 2

Magento 2 comes with a CLI that allows you to create a new temporary administrator user within few seconds. Change to the directory where your Magento installation ( such as app or bin folder ) is located and run the following command to create a user support with password 8cd98f00b20.

Voilà!

Now you can go to System > Permissions > All Users and update other users credentials.