Outlook doesn't display its windows correctly in coherence mode

Since I updated from Parallels version 25 to 26.1.1, Microsoft Outlook running in coherence mode doesn't display its windows properly. When reply windows open, they either don't appear at all or they appear truncated in the window frame of the main Outlook window. The drop-down menus from the top menu bar of the message windows gets truncated at the window's boundary rather than extending out past it. (Screen shots attached.)

How do I roll back? This is fairly disruptive. (I usually wait for the .1 release before updating to a new major version, but next ext year, I'll wait for the .2 release.)

Mac OS 15.7.1 / Mac OS M2 Max (Apple Silicon)
Parallels Desktop for Mac Pro 26.1.1
Parallels ARM Virtual Machine
Windows 11 Pro, Version 24H2, OS build 26100.6899, Windows Feature Experience Pack 1000.26100.253.0
Microsoft Outlook for Microsoft 365 MSO (Version 2510 Build 16.0.19328.20082) 64-bit

Updating to Mac OS 26 isn't an option yet, since Adobe Lightroom Classic 14 isn't certified to run on it and I'll want to wait at least a month after Lightroom Classic 15 arrives next week before upgrading Mac OS 26.

 

Oops, the Windows version is actually:

Windows 11 Pro, Version 25H2, 26200.6901, Windows Feature Experience Pack 1000.26100.253.0

(I looked at the wrong VM.)

 

Several of the users on my team are experiencing the same issue. Has anyone made any progress on a solution?

 

@ImraanN ,

I uninstalled KB5066835 and now Outlook is working properly again in coherence mode in 26.1.1. Thanks much.

 

I also uninstalled KB5066835 and now Outlook is working properly again.
BUT...
I currently have Windows Update on pause for 5 weeks. @ImraanN do you think it will be fixed by then? Not good to disable important security fixes for too long! But happy for now there's a short term fix. This was driving me crazy!

 

Unfortunately I might be a bit late in the game. Windows doesn't allow me to uninstall that particular update anymore.
Thus, I am stuck with that bug which really decreases productivity.

Is there a solution on the horizon? I hoped that today's update to 26.1.2 would solve it, but it didn't
Best, Nadym

 

I had to uninstall these updates before I could see KB5066835 in the uninstall list:

• Update for Microsoft Windows (KB5066128)
• Feature Update for Windows 11 25H2 via Enablement Package (KB5054156)

Still waiting to hear back from Parallels on an ETA for a real long-term fix here. Hopefully they will let us know soon. It's a painful bug!

 

I'm having the same problem here (macOS 15.7.1, Windows 11 Pro 24H2, Parallels Desktop 26.1.2).

And I can't find KB5066835
Nor can I find KB5066128 or KB5054156 ((
When were the three updates released?

Who can help?

 

FYI: Parallels just released Desktop 26.1.2 (build 57293) today, but the official release notes only say it "addresses overall stability and performance issues" with no mention of the Outlook/Coherence rendering bug described in this thread.
https://kb.parallels.com/131014

Can someone from Parallels please state clearly and unambiguously whether 26.1.2 includes a fix for the Outlook windows not displaying correctly in Coherence mode with KB5066835?

Right now, the only guidance we have is a temporary workaround that involves removing recent Windows security updates and pausing Windows Update for multiple weeks. That is not a reasonable long‑term solution for people who rely on Outlook all day and also need to keep their systems properly patched.

Several of us here have opened support tickets and have been dealing with this for a while, with very slow responses and no published ETA. This is a major productivity issue for paying customers, and the current level of silence/ambiguity is really frustrating. Clear communication from Parallels about what 26.1.2 does or does not fix (and when a proper fix is coming) would go a long way here.

Tagging @ImraanN and other Parallels staff here, since you previously acknowledged this as a known issue and recommended the current workaround.

 

Any further updates here? Still having this issue

 

You're not dreaming; it sounds like a Coherence bug in 26.1.1. The simplest workaround is to update the Outlook/Windows graphics drivers inside the virtual machine (VM) or quit Coherence. To roll back, use the "Previous Versions" tab in your Parallels account to remove version 26 and reinstall version 25.

 

This is a known issue with Outlook and Parallels Coherence Mode. Here are several solutions to try:

Quick Fixes to Try First:

1. Toggle Coherence Mode
   
   • Press Ctrl+Alt+C to exit Coherence Mode
     
     
   • Press Ctrl+Alt+C again to re-enter Coherence Mode
     
     
   • This often refreshes the window rendering
     
2. Restart Parallels Desktop
   
   • Completely quit Parallels Desktop (not just suspend)
     
     
   • Restart the virtual machine
     
3. Update Display Settings
   
   • In Parallels: Configure → Hardware → Graphics
     
     
   • Try changing between "Adaptive" and "Best for Retina" (if on Mac)
     
     
   • Adjust resolution settings
     

More Advanced Solutions:

1. Reinstall Parallels Tools
   
   • In the VM menu: Actions → Reinstall Parallels Tools
     
     
   • Restart the VM after installation
     
2. Change Outlook Display Settings
   
   • In Outlook: File → Options → Advanced
     
     
   • Under "Display", check/uncheck:
     
     • "Disable hardware graphics acceleration"
       
       
     • "Use discrete graphics card" (if available)
       
3. Run Outlook in Compatibility Mode
   
   • Right-click Outlook shortcut → Properties → Compatibility
     
     
   • Try different compatibility settings
     

If Using Multiple Monitors:

1. Display Configuration
   
   • Move Outlook to your primary/main display
     
     
   • Exit and re-enter Coherence Mode while on main display
     
     
   • Try running in single monitor mode first
     
2. Parallels Configuration
   
   • Configure → Hardware → Graphics
     
     
   • Set to "Scaled" instead of "Optimize for Retina"
     
     
   • Disable "Auto-adjust Windows size"
     

Last Resort Options:

1. Create a New Outlook Profile
   
   • Control Panel → Mail → Show Profiles → Add
     
     
   • Set as default and test
     
2. Use Windowed Mode Instead
   
   • If Coherence continues to have issues, use Windowed mode for Outlook specifically
     

Note: Make sure both Parallels Desktop and your guest Windows OS are fully updated, as display-related fixes are often included in updates.

Which version of Parallels Desktop and Windows are you using? This might help pinpoint a more specific solution.

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It's crazy to me that we have received NO response from Parallels about this. Are we the only people using their product these days?

 

I'm having this same issue but only when I have an external monitor connected. Is that what everyone else is experiencing? When I move back to my MacBook screen the windows aren't cut off.