Customization of 404 Parameter for non-existent short links allows to migrate safely to a new domain.
How it works
In the Short.io domain settings, you specify a link, for example, https://long.link/$1 to the 404 parameter. We will replace $1 with the slug of non-existing link. After that, when visitors end up on the error 404 page https://short.link/path-error they will be automatically redirected to https://link.link/path-error.
How to customize
1. Go to your Short.io account.
2. Open settings of your short domain.
3. Specify a long URL with $1 at the end to the Nonexistent shortlinks redirect field.
4. Save