Hi,
Thank you for sharing your question. I understand how alarming it is to suddenly be locked out of a file you access regularly, especially when an older password opens only a much older version of the document.
This situation can be both frustrating and worrying, particularly when the updated version of the file contains important or time‑sensitive information.
Similar cases reported by users show that Excel files stored in OneDrive may sometimes open an older version due to sync conflicts or file‑locking glitches. OneDrive may surface a past version if the newer file failed to sync correctly or if Excel created a conflicted copy during saving.
Other users have described Excel occasionally failing to recognize the correct password after saving or syncing, especially when working across devices or with OneDrive. In these situations, Microsoft recommended workarounds such as checking OneDrive version history to locate and restore the most recent version, or opening the document through Excel Online or another device to bypass the glitch.
Because you successfully opened an older snapshot using an old password, the most likely explanation is that OneDrive preserved a historic version while the latest version is either conflicted, corrupted, or locked behind a password mismatch bug. Checking OneDrive’s version history often reveals the correct, modern copy of the file and allows restoring it even if the password prompt fails. In addition, opening the file in Excel Online or downloading a temporary copy can sometimes trigger the correct password prompt.
I hope this helps.
Best Regards,
Noel