New user cannot login: plugin not loaded

[Geoffry Roberts]

Can anyone tell me what's going on?

I am running mysql 5.7.11 on osx 10.10.5 installed by homebrew.

Logged in as root.
I created a new user thus:
drop user 'igluser'@'localhost';
flush privileges;
CREATE USER 'igluser'@'localhost' IDENTIFIED WITH mysql_native_password BY 'igl';
flush privileges;

log out
log in:
mysql -u igluser -pigl

ERROR 1524 (HY000): Plugin '*38F4B19D564E82E6E3E7183D71673670B961C38D' is not loaded

I've never seen this before.

Thanks in advance.