How can I add Yahoo calendar to windows 10 calendar?

Hello Marci., welcome to the Microsoft community my name is Luiz Cruz, I am a Windows 10 expert user and would be happy to help you;

I understand that you are having problems adding your Yahoo email account to your Windows calendar;

In this case, I recommend that you follow the instructions below:

1. Update your Windows system to the latest version. You can go to “Settings”, click on “Update and security” and check for the latest updates. Make sure no additional updates are missing.
2. Check for updates to the Mail app in the Microsoft Store;

Launch the Microsoft Store and click on the three dots at the top right of the screen and go to "Downloads and updates";

If there are updates, click Get updates;

After making sure the system and application are up to date, try adding the account again;

If you still can't, try Restoring the Mail application;

Press Windows key + I and access settings;

Click on Applications;

Select the Email and Calendar application and click Advanced Options;

Scroll down and under Reset, click Reset;

The Application will be restored, after the process is finished, restart the computer and try to add the account again;

I hope I helped, see you soon!

Dear Marci.,understand that the procedures resolved the problem;

In this case, please kindly mark the issue as "Resolved" so that I can help others with the same problem;

I am very happy to help;

See you soon!

Thanks, actually

• removing the account
• full restart
• re-adding the account

seems to fix the issue.