Admin Page error "The page isn't redirecting properly" after changing base url in magento 2.1
It happened to me too, I could not access the admin back-end to change admin base URL setting. I did the following and it worked.
I ran this query
UPDATE core_config_data SET value = '1' WHERE path='web/secure/use_in_adminhtml'
directly in the database and then ran
php bin/magento cache:clean