The specified computer name '%1' contains one or more characters that are not allowed. Characters that are not valid include: ...

The specified computer name '%1' contains one or more characters that are not allowed. Characters that are not valid include:

 { | } ~ [ \ ] ^ ' : ; < = > ? @ ! " # $ %% ^ ` ( ) + / , * and .

Valid computer names may contain letters (a-z, A-Z), numbers (0-9), and hyphens, but no spaces or disallowed characters.