Microsoft 365 Insider | Outlook | Windows
A Microsoft application for managing email, calendars, contacts, and tasks across devices and platforms.
Just received Build 2508 V 16.0.19119.20000 and Outlook is working again.
After today's office 365 insider update, classic outlook will not open
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(28.799999999999997, 5%, 12%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ESM%3C/text%3E%3C/svg%3E)
Steve Mongeon
30
Reputation points
After this updating microsoft 365 insider this morning, classic Outlook will no longer open.
Microsoft 365 Insider | Outlook | Windows
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(73.60000000000001, 17%, 17%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EKC%3C/text%3E%3C/svg%3E)
Khai-Chew 0 Reputation points2025-07-18T11:27:59.68+00:00 There is another push of insider updates today. The latest version number is 16.0.19115.20000. Yet, the Outlook Classic is still unable to open.
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2 answers
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(28.799999999999997, 56.00000000000001%, 12%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EH%3C/text%3E%3C/svg%3E)
Happyrocks 15 Reputation points2025-07-22T15:15:34.78+00:00 -
Khai-Chew 0 Reputation points
2025-07-22T15:43:30.57+00:00 Thank you.
Yes, I have installed the latest push. It solved the problem. Outlook is now working.
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(96, 74%, 19%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ED%3C/text%3E%3C/svg%3E)
DarkWun 15 Reputation points2025-07-16T17:40:32.35+00:00 I am seeing the same after Microsoft 365 was updated to Beta 16.0.19113.2000 on July 15th. This is the error from Reliability Monitor.
The issue was resolved when I rolled back to the previous Beta build.
All other Microsoft 365 apps run without an issue.
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(265.6, 68%, 35%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ERP%3C/text%3E%3C/svg%3E)
Rajesh Pathak 1 Reputation point2025-07-17T09:41:00.6833333+00:00 I am facing the same issue.
Can you guide/explain how did you roll back to the previous version? -
Rajesh Pathak 1 Reputation point
2025-07-17T10:47:35.41+00:00 Can you kindly let me know the Version (xx.x.xxxxx.xxxx) for BetaChanneel that you Rolled back to?
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(176, 57.99999999999999%, 27%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EVG%3C/text%3E%3C/svg%3E)
Vince Granville 5 Reputation points2025-07-17T12:24:55.0566667+00:00 Absolutely. Definitely an issue with the latest Office Beta Insider build 16.0.19113.20000
I would not be surprised of an update before the end of the week or early next week to fix this.
Would like to know also in the interim the rollback steps please to the previous beta build?
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DarkWun 15 Reputation points
2025-07-17T14:10:00.0333333+00:00 These were the instructions I followed to revert to the previous beta build:
The build I reverted to was Version 2508 (Build 16.0.19107.20000) from July 9th.
You may need to reboot your computer after completing the steps in the linked support article before Outlook will run. When I tried to run it for the first time with out rebooting, outlook asked if I wanted to run it in safe mode. I declined, rebooted, and then ran Outlook. I did not receive the safe mode prompt after doing so.
Hopefully this helps!
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Rajesh Pathak 1 Reputation point
2025-07-17T15:19:21.7266667+00:00 Thank you so much. Will try and post the outcome. Obliged. 🙏
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Vince Granville 5 Reputation points
2025-07-17T16:03:48.6266667+00:00 Thank you very much for this information and the guide. Greatly appreciated.
Have a wonderful weekend ahead.
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Vince Granville 5 Reputation points
2025-07-17T18:27:52.3066667+00:00 Just to let you all know that the Insider beta build released today 17 July (16.0.19115.20000) still has not fixed Outlook, so hold off on this build.
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Rajesh Pathak 1 Reputation point
2025-07-21T05:42:00.12+00:00 Thank you DarkWun, it worked like a Charm.
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Happyrocks 15 Reputation points
2025-07-22T15:14:57.19+00:00 Just received Build 2508 V 16.0.19119.20000 and Outlook is working again.
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