Word 365 deletes any file with a hashtag in the name!

This is a known issue. See https://support.microsoft.com/en-us/office/locally-saved-word-files-with-capitalized-file-extensions-or-in-the-title-may-be-deleted-after-save-5e28f8c2-32d0-487b-b237-9c7c74d25f84

All operating systems have characters that are reserved and thus are illegal in file names. Please see this article about illegal characters in file names https://www.mtu.edu/umc/services/websites/writing/characters-avoid/

Thanks for the reference, but it is WAY too onerous.

I, too, have run into problems with various characters (in non-Microsoft desktop OS's), but I avoid using operating systems other than Windows, and I have files that date back 40 years (from Windows) and almost never have a problem. **** AFAIK, hashtag is fully supported by Windows -- please show me an official Microsoft document recommending avoiding hashtag. **** If you're interested, I could tell you how 20 years ago it caused a problem, but only relating to internet files and how Internet Explorer used them (file types *.mht or *.mhtml).

Also note that I am saving files on a local HDD, and the problem occurs even if I uninstall Onedrive.

Thanks for the prompt reply!

Answers to your Q's:

--Word for Microsoft 365 MSO (version 2409 build 16.0.18025.20030) 64-bit

--Saving locally. However, I do have Onedrive on. I uninstalled Onedrive, made no difference.

-- No error messages. It is as if the file never existed -- can't find a trace, except for dead shortcuts in Windows "Recent"

-- I haven't ever encountered anything like this. But I don't use Powerpoint and I don't have any files in Excel with hashtags. I'll do some more testing to see if it happens in other apps.

--Other details: I'm using Word on a local Windows 10 account with the latest updates. I.e., it is not associated with my Microsoft account. Computer is Lenovo E550 laptop with 12gb RAM and a ~500gb HDD. I'm using the user account -- it has Lenovo Vantage installed in the administrator account. The problem DOES occur in the administrator account.

Other things I will do is see if it happens :

(1) in Word's "safe mode" (?)

(2) if I delete all my word customizations

(3) if I create a new account in Windows and run from there

(4) if I download MSO on another Windows computer (a) with my customizations (b) without my customizations.

(5) in Windows safe mode.

Things I do regularly, and are 'clean':

Run SFC /Scannow

Run Chkdsk /r

Run perfmon /rel (it shows a rating of '6' which is not great)

Run windows memory checker (which is clean).

All operating systems have characters that are reserved and thus are illegal in file names. Please see this article about illegal characters in file names https://www.mtu.edu/umc/services/websites/writing/characters-avoid/

Hi,peterg321

Welcome to the Microsoft Support Community.

After reading your description carefully, let me summarize your situation to make sure I understand it correctly:

When you save a file containing the # symbol using the Save As function in Word 365, the file disappears after saving. You can see the file saved in Windows Explorer, but then the file disappears and can't be found in the Recycle Bin or through a Windows search.

You try to save a file containing the # symbol in the file name to the same folder and the file disappears. After copying a file from Windows Explorer and renaming it to a file name that contains the # symbol, opening and editing the file, the file disappears.

This is a really unusual problem and looks like a system aspect or an application problem. Based on your description your problem does not recur when saving the file using the Save As function, so in order to troubleshoot the problem further, I need to confirm the following information with you:

• Your Word version information (open any Word document > File > Account > About Word)
• Document save path, locally or in the OneDrive cloud? If you are using OneDrive or another synchronization service, special characters in the file name may cause synchronization issues to occur.
• Are there any error messages that pop up when a document disappears? If so, please provide details of the error message.
• Have you encountered similar issues with saving files in other Microsoft Office applications such as Excel or PowerPoint?

We understand the inconvenience this issue has caused you and hope to work with you to find the cause of the problem and resolve it as soon as possible. Thank you for your understanding and we look forward to hearing from you.

Cherry.Z- MSFT | Microsoft Forum Support Specialist