keytool error :java.io.IoException:Incorrect AVA format

I run this command:

keytool -genkeypair -alias alias -keyalg RSA -keysize 1024 -dname dn -keystore keystore

and this fails with "keytool error :java.io.IoException:Incorrect AVA format"

Just remove -dname:

keytool -genkeypair -alias alias -keyalg RSA -keysize 1024 -keystore keystore

and answer all questions directly, and you will be fine.