Class Zend not found in magento now. So for that, we have fixes for those classes which is currently using the same but we want to upgrade in latest magento 2.4.X versions.
common errors of Zend:
Error: Class Zend_Json not found
Error: Class Zend_Http_Client not found
Error: Class Zend_Filter not found
Error: Class Zend_Validate not found
How do I solve the above error?