Outlook (Classic) will not open

Question

Outlook (Classic) will not open

David Richmon 10

Outlook (Classic) will not open. Even the loading page does not start. All I get when I click the icon in the hourglass just for a quarter of a second. Outlook does not show up in task manager so I cannot even close it. It will not run in safe mode. I've even tried creating a new profile. It's as if the app is just gone although it is located in the proper directory. I have also tried Microsoft 365 repair both on and offline. I have tried reinstalling the app from both a download page i found and the Microsoft store page. The only thing that even worked was to go back to a previous restore point. But once Microsoft updated again the problem returned. I have also uninstalled the new Outlook (which does work) from my computer. But classic outlook doesn't work. the big issue for me is that classic Outlook has all my calendars and appointments. I need it back.

Howard Rachinski 5 Reputation points

2025-08-02T23:29:01.73+00:00

When will this bug be fixed so that we can use Outlook (Classic)?

2 answers

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Howard Rachinski 5 Reputation points

2025-08-02T23:29:01.73+00:00

When will this bug be fixed so that we can use Outlook (Classic)?

Answer 1

David Richmon 10

I am going to answer my own question. I'm a Microsoft 365 Insider. There is a bug in the most recent update. I reverted back to the previous build.

This is how:

Open Command Prompt as Administrator

Press Start, type cmd, then right-click Command Prompt and choose Run as administrator.

Run the Rollback Command

Paste the following command into the Command Prompt and press Enter:

cd %programfiles%\Common Files\Microsoft Shared\ClickToRun

Then you can run:

officec2rclient.exe /update user updatetoversion=16.0.19107.20000

Nghia-P 3,640 Reputation points Microsoft External Staff Moderator

2025-07-31T08:30:54.14+00:00

Hi David Richmon,

Have a good day and I hope you're doing well!

If you still have any concerns or questions, we’re here and happy to assist. Please feel free to reach out anytime.

Answer 2

Nghia-P 3,640 Microsoft External Staff Moderator

Hi David Richmon,

Have a good day and welcome to Microsoft Q&A Forum!

First of all, I want to sincerely thank you for sharing such a detailed description of the issue you encountered with Outlook (Classic) after updating to Microsoft 365 Beta (Build 16.0.19107.20000) from July 9th. I completely understand how frustrating and disruptive it can be, especially when Outlook contains important data like your calendar and appointments.

Please know that you are not alone! Many other customers have also reported similar issues with this update. Even the most recent Insider beta build released on July 17th (16.0.19115.20000) has not fully resolved the problem, and several users are still experiencing difficulties with Outlook.

I truly appreciate your initiative in troubleshooting and finding a solution by rolling back to a previous version. This is currently the most effective workaround for Insider users facing this issue. For anyone else experiencing similar problems, I highly recommend reverting to a previous, stable version of Office following Microsoft’s official instructions here: How to revert to an earlier version of Office and waiting for Microsoft to release a fully fixed update.

On a positive note, there is good news: the latest Insider Build 2508 V 16.0.19119.20000 has just been released, and Outlook is reported to be working normally again. You may want to try updating to this version to see if it resolves the issue for you.

Once again, thank you for sharing your experience and solution. Your feedback is extremely valuable and will help other users quickly identify and resolve similar problems.

Wishing you all the best in your work and with Microsoft products!

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment". User's image Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Nghia-P 3,640 Reputation points Microsoft External Staff Moderator

2025-07-25T08:34:55.5433333+00:00

Hi David Richmon,

I hope you're doing well. Just reaching out to see if you've had a chance to review the responses shared earlier. Any updates you can provide would be greatly appreciated. We're here to help!

If you feel this helped point you in the right direction, you're more than welcome to mark it as "Accepted Answer". This can make it easier for others facing a similar issue to find their way to a solution, too.
Nghia-P 3,640 Reputation points Microsoft External Staff Moderator

2025-07-28T04:39:41.1866667+00:00

Hi David Richmon,

Have a good day!

We’d love to hear back from you whenever you're ready. If there’s any update, please don’t hesitate to let us know.
Mark Walker 0 Reputation points

2025-09-03T16:27:03.4733333+00:00

Not sure this is 'fixed.' I bought a new PC with Windows 11 and fired it up last week - the last week of August. It went through all its gyrations to update and all that, and then I installed (from my subscription) what I assumed would be the 'latest and greatest' version of MS 365. It of course defaulted to the 'New' Outlook (which is NOT held to Earth by gravity - it SUCKS) and I clicked the toggle button to execute Outlook 'Classic.' It ran fine while I set up all my email accounts (some MS, some not) and imported all the .PST files and so on. All good - UNTIL I had to re-start the PC. Now Outlook Classic won't run at all - same problems as described above. (Hourglass for about one second, then nothing.) 'New' Outlook will launch, but it has none of my other multiple email accounts. Microsoft never seems to know when they have a good thing going and as a matter of course add features no one wants, and which are hard to manage. (Especially when migrating to a new PC.)
Kathy Ho 0 Reputation points

2025-09-09T22:23:29.5+00:00

This just happened me to me today for the first time! Microsoft, please advise!!
Mark Walker 0 Reputation points

2025-09-09T22:47:34.5233333+00:00

Don't hold your breath. I've heard nothing at all on the issues I reported. The idea of 'reverting' to a previous version, when I installed the 'latest and greatest' available on a brand new PC with my MS subscription is disingenuous. MS could just say, "Oh, never mind. New version doesn't work." So why bother releasing it?
James M. Thayer III 0 Reputation points

2025-09-15T21:38:45.1566667+00:00

100% agree. This whole "New" Outlook has been a boondoggle especially what has been done to Classic Outlook.

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Outlook (Classic) will not open

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