Need Help Fixing Windows 10 Adding a Mail Account, Error Code: 0x8007042b whenever I try to add gmail or Yahoo

EDIT: This has nothing to do with the Mail & Calendar client, nor Google itself. Something within Windows itself is causing the error. As I've removed the Mail & Calendar app, and just tried syncing google to my windows within settings>email & accounts>Add an account.

So I'll start with a quick explanation when this started happening, because it was just yesterday it was working perfectly fine. I simply updated my motherboard Bios yesterday and when I logged back into Windows 10 my mail client said I needed to update my login credentials. Giving me error Code 0x8007042b. Granted I could still access my email which was odd, but I was trying to clear this error message. So I removed all my accounts thinking I should just re-add them. Well that was mistake #1 Now I can no longer add any gmail accounts. This error happens when I click Add an account, then click Google or Yahoo!.

I've been searching around for a solution however everything I find doesn't work. Also lets be clear here, the problem isn't gmail. I'm not going to go into my gmail account and do the POP/IMAP WORKAROUND, because that's what that is, it is a workaround, NOT a solution to this error.

Other solutions I've tried that didn't work.

Go to your users folder (e.g. C:\Users\John).
Right click, select properties, Security, Advanced.
Click Add, select entity, advanced, search.
Click on ALL APPLICATION PACKAGES, accept. Select Full Control and apply (Ignore errors trying to apply permissions).
Then:

Click on start and type “Services”.
Right click on “Services” and select “Run as Administrator”.
In the Services Window, look for Credential Manager Service and “Stop” it.
Restart the computer and “Start” the Credential Manager Service and set it to “Automatic”.
Restart the computer and it should work fine.

Source: https://answers.microsoft.com/en-us/windows/forum/apps_windows_10-outlook_mail/cant-add-gmail-account-to-windows-10-mail-app/97d4e308-54a8-4afe-b74f-501b1ea0fa2a?page=12

I tried repairing my Windows 10 install and that didn't help.

However there is one thing I did find out. If I make a new user account on my Windows 10 install. I can then go into Mail and successfully add a google account. So this leads me to believe that the issue has something to do with the User account. I can't find where Mail keeps any of its settings or files that would cause this error from happening. As something is different from the new user I made to my Main User account that would be causing this error.

I'm not really sure why a motherboard bios update would cause this error to be happening, but it did.

Lots of kudos for reading this and understanding that the usual answers as "Solutions" do NOT work, and not suggesting them. Thank you.

I had this exact same issue a while back, (it's an very old issue apparently) and tried everything I knew and every suggestion which sounded logical ... but still could not add a new yahoo/google email. (The yahoo/google emails already on were working fine thought, but my damn PC would not let me add any other).

I was on the verge of a complete windows 10 re-installation when I thought "Why not try adding a new user? So I did, and, on the new account, I could add as many yahoo/google email accounts I wanted ... Bingo, as they say.

So what next? I thought. Should I simply use both accounts on my PC and switch between them when I wanted to see my new emails? No ... I simple took all the information from my 'dud' account (the one which hated me adding new emails) to the new account which was almost akin to resetting my windows without the hassles of installing all my programs and apps and bookmarks ...

So I set about shifting my files from my dud account to the new one using what I like to call the side by side method. (Just make sure new account is Admin) I opened my 'dud' account user folders (C/user/name) through my new account, giving permissions for the files to open.

Then, once open, I transferred the old files I needed onto the new account folders, (ie C/user/name/music to pc/music or C/user/name/documents to pc/documents) Once the folders/files were in the new account I simply deleted the 'dud' account using windows 'user account' deletion process and was left with my new account which has worked perfectly since.

I have an idea how this issue occurs, and, unless you try adding a new google/yahoo account you won't know if you're PC has this issue at all..

As always, back-up your stuff before you try anything you're unsure of ... or anything at all.