Safari won't open Yahoo.

Hi TuanNgo2023,

We appreciate you reaching out to us.

We’d like to gather additional details that may help us be in a better position to assist you.

Are you getting an error message?

Have you had the chance to try a different Wi-Fi network?

Is the issue isolated to accessing Yahoo?

In the meantime, let’s test if the issue persists on a newly created user account. 

1. "On your Mac, choose Apple menu > System Settings, then click Users & Groups  in the sidebar. (You may need to scroll down.)
2. Click the Add Account button below the list of users on the right (you may be asked to enter your password.)
3. Click the New Account pop-up menu, then choose a type of user.
4. Enter a full name for the new user. An account name is generated automatically. To use a different account name, enter it now—you can’t change it later.
5. Enter a password for the user, then enter it again to verify. Enter a password hint to help the user remember their password.
6. Click Create User."

You can use the article below as a reference.

Add a user or group on Mac - Apple Support

If you are experiencing the issue when signed in on a different user account, please check if the issue persists while on safe mode. Safe mode does a basic check of your startup disk, similar to using First Aid in Disk Utility.

Performing this step may help resolve the issue, or further isolate the issue.

Below is an article to help guide you through the process.

Use safe mode on your Mac - Apple Support

Take care!