Cannot Open Office 2019 OutLook365

JamesMNTexas 

If you've tried OLK Safe Mode (outlook /safe) that means no 3rd party interference that is contributing to the issue.

To wit,

IF OLK (Outlook) is stuck in loading profile, It could be somethings on the authentication of your OLK instance against Exchange Online (EXOL) per past experience.

I'd suggest to ensure below is configured then try to re-open OLK again,

Office 2019 is using modern auth:

• Go to: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity

  Add DWORD:

  "EnableADAL"= 1

OLK (Outlook) is using modern auth: 

• Recommend that users force Outlook to use Modern Authentication. To do that, set the DWORD value of the following registry key to 1. 
  HKEY_CURRENT_USER\Software\Microsoft\Exchange\AlwaysUseMSOAuthForAutoDiscover

  • From <https://docs.microsoft.com/en-us/exchange/troubleshoot/modern-authentication/modern-authentication-configuration>

EXOL is using modern auth: 

1. To enable modern authentication, go to the admin center at https://admin.microsoft.com.
2. Choose Settings > Services & add-ins and then choose Modern authentication from the list.
3. Check the Enable modern authentication box in the Modern authentication panel.

Polite as usual,

BFN

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