cannot grant privileges to mysql database

First, Identify the user you are logged in as:

 select user(); select current_user();

The result for the first command is what you attempted to login as, the second is what you actually connected as. Confirm that you are logged in as root@localhost in mysql.

The issue was that the installation I came up with did not provide Grant_priv to root@localhost. Here is how you can check.

mysql> SELECT host,user,password,Grant_priv,Super_priv FROM mysql.user;
+-----------+------------------+-------------------------------------------+------------+------------+
| host      | user             | password                                  | Grant_priv | Super_priv |
+-----------+------------------+-------------------------------------------+------------+------------+
| localhost | root             | ***************************************** | N          | Y          |
| localhost | debian-sys-maint | ***************************************** | Y          | Y          |
| localhost | staging          | ***************************************** | N          | N          |
+-----------+------------------+-------------------------------------------+------------+------------+

You can see that the Grant_priv is set to N for root@localhost. This needs to be Y. Here is how I fixed this:

UPDATE mysql.user SET Grant_priv='Y', Super_priv='Y' WHERE User='root';
FLUSH PRIVILEGES;
GRANT ALL ON *.* TO 'root'@'localhost';

I did get some permission error, but when I logged back in, it was fine.

For those who still stumble upon this like I did, it's worth checking to make sure the attempted GRANT does not already exist:

SHOW GRANTS FOR username;

In my case, the error was not actually because there was a permission error, but because the GRANT already existed.

try flushing privileges after granting permissions

GRANT ALL PRIVILEGES ON staging.* TO 'staging'@'localhost' IDENTIFIED BY 'test';
FLUSH PRIVILEGES;