I cannot login to my outlook email, how do I fix this problem?

I was using the Oulook APP and my email server is Yahoo. I posted screenshots of my issue that falls on page three of this thread of people having issues. I just directly used Yahoo to check my emails until yesterday, I tried using Outlook and noticed the toggle to switch back to the classic version and was able to login and begin receiving emails again. Everything is working and I think I will stick with the classic. Only downside was my contacts were gone.

Sorry I am confused now. Outlook APP is the same thing as Classic Outlook. So what do you mean that you switched from APP to Classic? What do you mean by /APP does not work/ but /Classic works/?

By APP do you mean "New Outlook" which is browser based and is not an app (downloaded program)?

Or by APP do you mean the Office365 version (Outlook 2024?) and that you switched to a previous version (Outlook 2021 or Outlook 2016)? In this case I believe that "Classic Outlook" refers to all versions of Outlook that are downloaded programs (O365 or prior) and which are not the browser based (New) outlook.

In other words, there are only 2 classes of Outlooks. New Outlook which is browser based, and Classic Outlook which is an app (downloaded program).

Yes the Office365 version

So Outlook 365 is not an APP. It is just a simple browser to Outlook.com in the cloud. It is called New Outlook, and is not downloaded. Your mail is stored and managed in the cloud. You don't have access to your emails if you go offline.