Just follow the guidelines mentioned in the blog to fix this issue.
Solution: Yahoo Email App not working on Android
1. First, you need, verify that you are using the latest version of the Yahoo Email App and Android. Make sure to clear the cache and App data 2. If you are facing sign-in issue then try to verify the account recovery option that is stored in your Android and try to update it. then, Use Account key to get access to your Yahoo email account in Yahoo Email app. 3. You should have an active internet connection and also check the App Permission by going to the Setting option of your Android device.
Sometimes, you have any issue after following these steps you can call Yahoo Help Number +1-800-318-4042 the USA. We give instant support for all your Yahoo email account.