Problem after clearing the cache and installing the payment module.

[przemyslaw5e24]

Hi

I installed the module and cleared the caches. I got this error when trying to log in a client. Fatal error: Uncaught Error: Undefined class constant HASH_VERSION_MD5 /app/code/core/Mage/Customer/Model/Observer.php

How to solve this problem?

Thank you

[LitCommerce Expert]

This problem comes from the Mage module. You should disable this module from your project
php bin/magento module:disable Mage_Customer
Or alternatively, you can put debug in the file /app/code/core/Mage/Customer/Model/Observer.php so you can find out the reason for the error in this file