Outlook for Mac 2016 keeps asking for credentials

Outlook keeps asking for Office 365 credentials to be entered.

Caused by issues with keychain.

Fix Outlook 2016 For Mac Keeps Asking Password of Office 365 Account

To troubleshoot this problem, you need to delete any cached passwords for your account, and also delete any authentication tokens from the keychain. To do this, follow the steps given below:

1. First of all, you need to quit Outlook and all other Office applications.
2. Now, start Keychain Access by using one of the following methods:
   1. Click on the Finder application, click Utilities on the Go menu, and then double-click Keychain Access.
   2. Under Spotlight Search, type Keychain Access, and then double-click Keychain Access in the search results.
3. In Keychain Access, enter Exchange in the search field.
4. Under the search result, select each item to view the Account that’s listed at the top, and then click Delete. You have to repeat this step to delete all items for your Exchange account.
5. Inside the search field, enter adal.
6. Then, select all items whose type is MicrosoftOffice15_2_Data: ADAL:<GUID>, and then click on the Delete button.
7. Under the search field, type office.
8. After that, select the items that are named Microsoft Office Identities Cache 2 and Microsoft Office Identities Settings 2, and then click Delete.
9. Now, Quit Keychain Access.