Unable to login into my second MS 365 account

Can you go check your Windows Settings > Windows update, and see if you might have  KB5085516 available to install?

KB5085516 was released on March 21st to address Microsoft account sign in issue among some apps caused by KB5079473 https://support.microsoft.com/topic/march-21-2026-kb5085516-os-builds-26200-8039-and-26100-8039-out-of-band-09e85404-1cb6-4ed4-9ca5-3e40d74307b9

Follow these steps to restore sign-in for the second Microsoft 365/OneDrive account that reports “check your internet connection” even though the PC is online:

1. Verify the account itself works
   • In a browser, sign in to the Microsoft Account dashboard using the affected email (for example, the outlook.com address) to confirm the username/password are valid and the account is not blocked:
     • Go to the Microsoft Account dashboard and sign in.
   • If sign-in fails there, use the Microsoft account sign-in help to diagnose and fix the account issue before returning to the PC:
     • Use the Sign-in Helper tool.
2. Check for known OneDrive/Microsoft account sign-in issues on the PC
   • Some recent issues cause Microsoft apps (including OneDrive and Office) to say there is no internet connection even when connected.
   • On the affected PC, open Settings > Windows Update and install any pending updates, especially any update that mentions fixing Microsoft account or OneDrive sign-in issues.
   • After updates install, restart the PC and try signing in again to Microsoft 365/Office and OneDrive.
3. Confirm OneDrive and Office are up to date
   • Make sure the latest OneDrive client is installed:
     • If needed, download the latest OneDrive sync app from the Microsoft OneDrive app page and install it.
   • Open any Office app (for example Word) and try Sign in again with the outlook.com account.
4. Reconnect OneDrive if it was partially signed out
   • If the OneDrive icon is visible in the taskbar notification area:
     1. Select the OneDrive icon.
     2. Go to Help & Settings > Settings.
     3. On the Account tab, verify that the correct account (the outlook.com or arrowhead.media account) is shown. If not, sign out there and sign back in with the correct account.
5. If OneDrive/Office still say “not connected to the internet” only on this PC
   • This usually indicates a local client or configuration problem, not the account itself (since the browser sign-in works).
   • Unlink and relink OneDrive to clear any bad account configuration:
     • Follow the steps in Unlink and re-link OneDrive from the OneDrive support article.
   • If that does not help, uninstall and reinstall OneDrive:
     1. Open Start, type Programs, select Add or remove programs.
     2. Under Apps & features, select Microsoft OneDrive > Uninstall.
     3. Download and reinstall from the Microsoft OneDrive app, then sign in with the second account.
6. If Microsoft 365 apps themselves cannot sign in
   • Use the Microsoft 365 sign-in helper to detect account-level issues that might be blocking activation or sign-in:
     • Start the Sign-in helper and follow the guided steps.

If the account works in the browser, Windows is fully updated, and reinstalling OneDrive resolves the “no internet” message, Microsoft 365 features on the PC should re-activate once the correct account is signed in again.

References:

• I can't sign in to my Microsoft account
• Can't sign in to OneDrive
• Fixes or workarounds for recent issues in OneDrive
• Sign in to Microsoft 365
• Error 0x8004de80 or 0x8004de86 when signing in to OneDrive
• Unable to sign into account - says I am not connected to Internet but I am - Microsoft Q&A
• OneDrive says I'm not connected to the internet - but I am! - Microsoft Q&A