EXCEL 365 Switch Modes section / Dark Mode button missing from View Ribbon after Project Pro install

Question

Hello,

I had Project Pro installed on my work computer. Following this, I no longer had the Switch modes section and Dark mode button option on the View ribbon in Excel. I have Microsoft 365 installed.

I tried uninstalling Project Pro and running a Repair Online for Microsoft 365 applications. This did not revert the issue.

I also tried re-adding Dark mode from the Customize Ribbon menu under View under Main Tabs, but the option does not appear there.

The Project Pro version installed is Project Pro 2016 64-bit. I wonder if being such an old version is what's caused certain features of Excel to be disabled.

Has anyone else encountered this issue and know a fix? Please advise.

Thank you

Windows 11

Microsoft Excel / Project Pro / Office 365

Answer 1

Dear @PK,

Thank you for posting your question in the Microsoft Q&A forum.

We apologize for any inconvenience you may encounter when using our services/ products. Based on your description:

Mixed installation technologies: Project Pro 2016 uses the older MSI installer, while Microsoft 365 apps use Click-to-Run. Mixing these often disables newer UI features in Office apps.

Even with updates, MSI-based Project 2016 will keep causing conflicts. Microsoft officially recommends not mixing MSI and Click-to-Run installations.

Kindly try these following steps:

Remove MSI-based Project Pro completely

• Go to Control Panel → Programs → Uninstall a program.
• Remove Project Pro 2016.
• Run Microsoft Support and Recovery Assistant (SaRA) to clean residual MSI components.

Reinstall Microsoft 365 Apps

• Download the latest Click-to-Run installer from your Microsoft 365 portal.
• This ensures all modern UI features (including Dark Mode) are restored.

If you need Project:

• Install Project Plan 3 or Plan 5 (subscription-based) from Microsoft 365, which uses Click-to-Run and is fully compatible.
• Avoid mixing MSI and Click-to-Run products.

Verify Dark Mode after reinstall

• Open Excel > File > Account > Office Theme > Black.
• Then go to View > Switch Modes to toggle full dark mode.

Here are some reference to uninstall Microsoft apps:

• Uninstall Microsoft 365 from a PC - Microsoft Support
• Uninstall Office with Microsoft Support and Recovery Assistant in Firefox - Microsoft Support
• Office uninstall with Microsoft Support and Recovery Assistant - Microsoft 365 | Microsoft Learn

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Answer 2

@Huy-K thanks for the reply.

It turns out what I had done originally was eventually set to work, it just hadn't worked yet.

The Project Pro uninstall and M365 Repair Online steps I performed didn't take immediate effect to restore Excel Dark mode, but some time later, the MS apps I had open (they were closed during the Repair Online step) prompted me to restart them again. Once I restarted them again, I now had Dark Mode restored in Excel.

If I need Project going forward, I will request the subscription version if that's an option with my organization.

Thank you again!