I recently updated Mautic, and then got too many redirects and could not log in:
This is what got me back running:
$ cd /your/mautic/directory
$ php app/console cache:clear
$ composer install
$ php app/console doctrine:migrations:migrate
$ php app/console doctrine:schema:update –dump-sql
** check ^^ output and make sure you are ok with it.. that it wont break you
$ php app/console doctrine:schema:update –force
After that, I got an error: The site is currently offline due to encountering an error <– this post shows how I resolved that.
Full instructions: https://github.com/mautic/mautic