404 error appears when entering Magento admin panel.

Sometimes migration to the other server can cause some problems such as error 404. The most frequent reason is a hosting switching.

And if you want to fix it, first of all you have to commit the next query:

SET FOREIGN_KEY_CHECKS=0;
UPDATE `core_store` SET store_id = 0 WHERE code='admin';
UPDATE `core_store_group` SET group_id = 0 WHERE name='Default';
UPDATE `core_website` SET website_id = 0 WHERE code='admin';
UPDATE `customer_group` SET customer_group_id = 0 WHERE customer_group_code='NOT LOGGED IN';
SET FOREIGN_KEY_CHECKS=1;

Next, clear your cache folder in / var / cache /. If you own enterprise version or FPC has been installed – then folder /var/full_page_cache/ needs to be cleared as well.
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