To install and use classic Outlook on a Windows PC when new Outlook is installed and sign-in is failing, follow these steps:
- Install classic Outlook
- Go to the article Install or reinstall classic Outlook on a Windows PC:
- Use the store install link in You can't open classic Outlook on a new Windows PC (this article is referenced from the “go back to classic Outlook” fix article).
- In the Select a language and download classic Outlook section, choose the appropriate language (for example, Spanish, Russian, etc.) and select the corresponding Download link.
- Run the downloaded installer and complete setup.
- Alternatively, try installing classic Outlook directly from the Microsoft Store using the tip in the same article.
- If the “Go back to classic Outlook” button does nothing
- This issue was previously known and has been fixed.
- As a workaround (if still affected), use the store install link in the article Go back to classic Outlook button not working correctly in new Outlook, which points to You can't open classic Outlook on a new Windows PC and then install classic Outlook from there.
- When classic Outlook appears randomly
- Classic Outlook and new Outlook can both be installed.
- New Outlook may open when switching via the Try the new Outlook toggle in classic Outlook, and classic Outlook can be opened again when the toggle is used in new Outlook (per the “Switch to new Outlook for Windows” behavior).
- Ensure classic Outlook is installed via the steps above, then pin the classic Outlook icon to the taskbar or Start menu and launch it directly instead of using the toggle.
If using a work or school account and installation still fails, contact the organization’s IT admin for assistance.
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