Thanks — that combination is the key:
- You’re using POP/IMAP in classic Outlook, and
- You have KB5074109 installed (Jan 13, 2026 cumulative update), and
- You run ESET (which often installs an Outlook/email scanning integration even if you don’t see it as an “app”).
Microsoft has acknowledged that
KB5074109 can cause classic Outlook POP profiles to hang / freeze / and “not exit properly” (Outlook.exe stays running) and they list it as
Investigating. teinstall Windows or Office
—it strongly points to an update regression** (possibly made worse by email/AV hooks).
Below is the best “least risky → most drastic” plan.
1) Confirm you’re on the affected Windows build
Open
Win + R → winver
If you see OS build
26100.7623 (or similar branch mentioned with KB5074109), you’re in the exact window where this regression is reported.
2) Quick mitigation: stop Outlook stuck
When Outlook won’t close (after editing Contacts), do this instead of holding the power button:
- Task Manager → Details tab → OUTLOOK.EXE → End task
(Details tab is important: sometimes the “Processes” tab behaves differently.
- Or use Win + R →
cmd → then run:
taskkill /f /im outlook.exe
This avoids file corruption risk from forced power-offs.
3) Test whether ESET is making it worse (very common)
Even if you “only have ESET”, it can still hook into Outlook via:
- Outlook add-in (COM add-in), and/or
- “Email client protection” / SSL scanning.
A) Check Outlook Add-ins
Outlook →
File → Options → Add-ins → Manage COM Add-ins → Go
- If you see anything ESET-related, untick it temporarily and test.
B) Temporarily disable ESET email scanning (test only)
Inside ESET, look for something like:
- Email client protection, Email scanning, or SSL/TLS scanning
Temporarily disable just that component, reboot, then test:
- add/edit a contact
- close Outlook
If this fixes the “won’t exit” problem, then the best long-term solution is usually:
- update ESET to the latest build, and/or
- keep email scanning off, and rely on file-system protection instead (safer than breaking Outlook).
4) Determine if it’s POP-specific in your profile
Microsoft’s advisory points most strongly to
POP profiles.
So please check: does the “won’t close after editing contacts is running
only an IMAP account, or only when the
POP account is present?
If POP is involved, a practical workaround is:
- Create a new Outlook profile and configure IMAP only (or move away from POP if your provider supports it).
5) If you need a reliable fix now: uninstall KB5074109 (trade-off: security)
Because Microsoft is still “Investigating” , the only “hard” workaround some users use is uninstalling the KB.
Warning: Remate reduces security. Do this only if the issue is seriously impacting you.
Try:
- Settings → Windows Update → Update history → Uninstall updates
- Uninstall KB5074109
- Reboot
- Then pause updates for a short period (e.g., 1–2 weeks) until Microsoft ships a fix.
If Windows doesn’t allow uninstall (sometimes it happens), there are DISM methods, but I’d prefer to guide you carefully before you do anything advanced.
6) One thing I need from you (so I can point to the exact “best next step”)
1) In Outlook: what accounts are configured—
how many POP and
how many IMAP?
2) When it fails to close, is
OUTLOOK.EXE still visible in Task Manager → Details?
3) Please paste the result of
winver (version + OS build).
With those 3 answers, I’ll tell you whether the smartest move is:
- (A) disable ESET email integration first, or
- (B) move POP → IMAP / new profile, or
- (C) uninstall KB5074109 and pause updates until the Microsoft fix lands.