MAMP database upload problem
I assume you are trying to import this via phpMyAdmin and that the file is an standard DB dump.

I would recommend either doing this via drush or the mysql command line.  E.g.:

drush @mysite sql-cli &lt; \backup\my-dump.sql


Note:  drush @mysite status should show db schema and user name.

or 

mysql -u user -p d8-database-schema-name &lt; \backup\my-dump.sql


Another alternative would be to use the MySQL Workbench Tool.  Excellent GUI tool that runs on any OS and can even access databases via SSH.  Set up a connection to your DB, then load the dump as a script.  Make sure your target database schema is selected as default.