Word For Mac Quitting Due to Memory Leak

Ben L 25 Reputation points
2026-04-06T14:42:27.2366667+00:00

Word crashes after about 1 day's use, every time. I can see that it is being killed by my Mac due to a memory leak (Activity Monitor shows the memory usage of Word growing steadily from about 500M to 10G at which point my Mac presumably kills it). I don't know why the memory leak is occurring.

Details:

  • I'm using a Macbook Pro (M1 series).
  • I am a member of a Microsoft 365 Family account. With that subscription, I downloaded Word from the Mac App Store.
  • I used to have no issues. The issues seemed to start when I upgraded my Mac to Tahoe.
  • I tried uninstalling Word and reinstalling with an older version that used to work, but that one had the same issue. This leads me to think that the issue is due to the Tahoe upgrade.
  • The issue occurs with any Word doc.
  • Issue has persisted for around 5 months now. I've gone through various Word updates since then (and Mac updates), but none of them fix the issue.
  • When Word crashes, there is no warning or error message shown (this is probably expected though because my Mac is killing it).

What can I try to fix this issue?

Microsoft 365 and Office | Word | For home | MacOS

6 answers

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  1. Steven Kaufman 50 Reputation points
    2026-06-11T13:00:42.82+00:00

    Hi, folks: I had a long chat with MS tech support yesterday. The culprit is NavPane. Because it's continually reindexing the headings, it's not releasing memory so usage climbs until macOS kills the app. To test the theory, I've left my file open all night--the one with extensive use of headings that kept leading Word to quit. NavPane closed: 680MB; no crash. Open NavPane; memory usage climbs steadily to about 6GB; then Word quits. I see this on my Mac Studio and my MacBook Pro .

    This is a known bug to Microsoft. They won't release a fix date. Their release page with office app downloads will only say "bug fixes and improvements." There's no way to find exactly if and when they'll correct this problem.

    Here are my workarounds:

    • Don't leave NavPane open all the time. I'm opening it when I need to jump around, then closing it. Memory usage will climb when it's open, but stops once it's closed. This will lengthen the time before the program crashes.
    • I created a Table of Contents, then preceded it with "zzz." I do a quick search for "zzz", then use the TOC's built-in hyperlinks to jump around. It's not nearly as convenient as having the entire doc outline on the left side--and you have to update the field constantly if you add new Heading style content--but it is a reasonable NavPane alternative.
    • Because the issue is related to macOS memory usage, downgrading to version 16.78 - 16.82 until there's a fix was recommended by the first tech with whom I spoke, but not by his supervisor. It's likely that older versions of Word will also exhibit this behavior.

    I'm writing a novel, so sparing use of NavPane can work for me. Open it only when I need to jump around, then close it. Use TOC to study the chapter and scene outline for longer periods of time without a memory impact. It sucks--NavPane does both so conveniently--but it's not worth the anxiety of hitting Cmd+S every fifth word and waiting for the program to crash. I use Dropbox, so saving the novel in OneDrive isn't an option for me.

    Hope this helps. At least I know the source of the issue, proved that it's repeatable, and that it's on MS radar. Keeping my fingers crossed that this will eventually lead to a fix.

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  2. Bob Jones AKA CyberTaz MVP 437.5K Reputation points
    2026-04-06T16:11:13.25+00:00

    The best solution is to avoid the problem by not leaving any program running for extended periods, especially if not in frequent use. Further, any documents left open for extended periods are subject to corruption and/or loss of content. As the adage states, "An ounce of prevention is worth a pound of cure." šŸ™‚

    Likewise ā€” contrary to what the industry intimates ā€” the computer should be restarted periodically. Optimally, shut down nightly rather than relying on something such as sleep which is nothing more than an energy saving function.

    If the issue seems related to Tahoe be sure to keep it fully updated. Tahoe has exhibited a number of early-onset issues. Perhaps Apple Support can provide some assistance or clarification.

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  3. Martin Gifford 15 Reputation points
    2026-08-12T01:10:31.7433333+00:00

    Maybe the navigation pane Memory Leak has been fixed with the latest update 16.112. I have a 300,000 word document and it seemed to peak around 940 mb. But I only tested for 15 minutes. Keen to hear others' experience.

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  4. Martin Gifford 15 Reputation points
    2026-05-25T09:50:29.4533333+00:00

    Navigation Pane could be the culprit. Word has been crashing for me constantly since Tahoe. I tried all the solutions provided online. Then I closed the spellchecker and connected services. Memory stabilised. But I realised that I also turned off the navigation pages so that I had room on my screen to watch Activity Monitor as I typed. Then I turned the Navigation Pane back on, in addition to the Activity Monitor, and memory usage started rising. So I think that's the cause.

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  5. Francisco Montilla 30,705 Reputation points Independent Advisor
    2026-04-06T15:18:57.9466667+00:00

    Hello,

    The App Store version of Word runs in a strict sandbox, and sometimes OS-level changes mess with how it releases memory. I would like to isolate exactly what is triggering the leak before giving you a specific fix to try.

    • Do you use any add-ins or reference managers linked to Word?
    • Also, if you open a completely blank document and just leave it alone for the day, does Activity Monitor still show the RAM skyrocketing to 10GB, or does it only happen with specific documents that have lots of formatting and custom fonts?

    As a diagnostic test, try booting your Mac into Safe Mode, open a regular document, and keep an eye on Activity Monitor for a few hours. That will tell us if a system background process or a corrupted font cache is fighting with Word. Let me know the results so we can figure out the actual cause.

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