Word for Mac leaves temporary files on Synology NAS after save and close over SMB

Question

Hello,

I am experiencing a recurring issue with Microsoft Word for Mac when editing documents stored on a Synology NAS over SMB.

When a Word document is opened directly from a Synology NAS share, edited, saved, and then closed, Word leaves temporary files on the NAS.

These temporary files do not disappear automatically after the document is closed, and they accumulate over time on the NAS.

Answer 1

Check that your user account has full permissions to create, rename and delete files on the NAS.

As an alternate method, create the files on your local hard disk, then move them to the NAS when you're finished with them.

If all else fails, just delete the temp files when Word is closed.

Answer 2

Your screen shot does not show temp files. Temp files are single files that replace the first 2 characters of the file name with ~$. Are you referring to the folders in your screen shot?

You may have an issue either with the setup of your Synology server or with Office. I use Word for Mac with a Synology server on a daily basis and do not see any similar problem.

To test, try creating a new user account in System Settings>Users & Groups. Then sign into that account and see if the issue persists. If it goes away, there is a problem with the user information in your Office installation. You should be able to fix this by uninstalling following these steps: Uninstall Office for Mac Then reinstall from the Subscriptions page of your Microsoft account.

Answer 3

Word creates several kinds of temporary files whenever a document is opened, edited, saved, or when AutoRecover runs. These files are expected and are part of Word’s data‑integrity and performance design, especially when working across a network share such as an SMB share on a NAS.

Key points relevant to the Synology NAS scenario:

1. When a previously saved file is opened from a share, Word creates an owner file in the same directory as the source file. This file name starts with ~$ followed by the rest of the original file name and contains the logon name of the user who opened the document. It is used to detect when a document is already open by another user.
2. When Word saves a document, it first writes the content to a temporary file and only then deletes the previous version and renames the temporary file to the original name. This protects the document from corruption if a problem occurs during the save.
3. When copying and pasting between documents, Word may create additional temporary files in the same directory as the source file, especially if the source file is saved or closed while the Clipboard still references its content.
4. Word normally deletes these temporary files when the document is closed and Word shuts down normally. If there is any interruption in the save/close process (for example, a network glitch, permission issue, or other environmental problem on the NAS), the temporary files can be left behind and accumulate.
5. On macOS as well as Windows, if something environmental breaks the save or AutoRecover process, Word can report disk‑related errors and leave behind ~Word Work File S{…}.tmp or similar files. Updating Office for Mac to the latest build is recommended to reduce such issues.

Practical mitigation steps based on this behavior:

• Ensure Office for Mac is fully updated so that the save/AutoRecover logic and network handling include the latest fixes.
• Verify that the SMB share on the Synology NAS allows Word to create, rename, and delete files in the document folders without interruption; intermittent network or permission issues will cause temporary files to remain.
• Periodically clean up leftover temporary files on the NAS (files starting with ~$ or with temporary names) when no one has the corresponding documents open.
• Prefer working with AutoRecover and other temporary locations on a local path where possible, as Word performs best when its temporary/scratch files are on local storage.

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References:

• Description of how Word creates temporary files
• Performance issues with Auto-Recover location on network share
• There is a serious disk error on when attempting to save, copy and paste or create auto recovery files in Office for Mac