The command has indeed failed with message:
Attribute for canonical specified twice.
The command has indeed failed with message:
key 'polymorphic' has been already set.
The command has indeed failed with message:
Invalid value 'foo' for key polymorphic
use one of {yes, no}
The command has indeed failed with message:
Invalid syntax polymorphic(foo), try polymorphic={yes, no} instead.
The command has indeed failed with message:
Invalid syntax polymorphic(foo, bar), try polymorphic={yes, no} instead.