The error you have is out of the Juju client which is deployed as a snap. I'm going to guess that you had some sort of snap upgrade issue and it's unrelated to rebooting the controller as it does not use a snap for any part of its operations currently.
Can you specify what you see for snap info juju and verify the version on the controller "juju show-controller". My guess is that the controller was 2.4.6, you got a 2.4.7 snap upgrade, and that upgrade somehow didn't complete successfully.
The error you have is out of the Juju client which is deployed as a snap. I'm going to guess that you had some sort of snap upgrade issue and it's unrelated to rebooting the controller as it does not use a snap for any part of its operations currently.
Can you specify what you see for snap info juju and verify the version on the controller "juju show-controller". My guess is that the controller was 2.4.6, you got a 2.4.7 snap upgrade, and that upgrade somehow didn't complete successfully.