In case some of your short links still point to pages which no longer exist, you can prevent your visitors from seeing the 404 error by configuring the Page not found redirect option from your short domain settings.
When users browse the old short link they will be redirected to a new working page.
To activate redirection
Sign in to your Short.io account.
Navigate to Domain settings -> Redirects:
Click on Configure next to Page not found redirect.
In the next Redirect configuration screen enter the URL of your new domain:
Click on Confirm.
You can review the newly created short link:
For example, if your visitors try to browse a short link pointing to your nonexistent page:
they will be redirected the new domain's page which you specified.