Temporary Error 1
Occasionally, issues in Yahoo Mail can cause a temporary error. "Temporary Error 1," which can also appear as "UserOpenFailed," is one of these.
Don’t worry, this error will usually correct itself within a few minutes to a few hours.
Don't wait! Get your email while the problem corrects itself on a computer. Download the Yahoo Mail app for iOS and Android devices and access your email on a smartphone now.
Try these steps to fix the error on a computer: