Unable to connect to an Office 365 / Outlook account
Office 365 connections normally fail due to one of two things.
The account does not qualify as an enterprise Office 365 account so the normal Office 365 connection won't work (we rely on Microsoft's provided authentication library, which does not work with personal accounts or at times self-hosted O365 accounts). Instead, you'll have to try connecting to it as a normal Exchange account (from the account list, select Exchange instead of Office 365) and supply a login / password. Depending on the account security settings, you may need to generate and use an app specific password to successfully connect. Here is an article on how to generate one. Please also note - BusyCal does not support Exchange ActiveSync, in case that is the only protocol your server has been configured to support. BusyCal requires Exchange Web Services (EWS) and relies on Exchange Auto Discovery to connect.
We have additional information about this in this article.
If your account is an Office 365 account, then setting it up as an Exchange account will not work with our apps. However, in case that fails too (usually with an error code such as -5005), then the Office 365 portal settings have blocked or not given the app explicit consent to access the account - unfortunately without the appropriate permissions it won't allow BusyCal to connect as normally all 3rd party apps are blocked by default.
This is not uncommon as most organizations will allow the built-in Apple Calendar app on macOS to connect to their servers and will not allow other 3rd party apps.
Office 365 installation may have very restrictive settings, disallowing 3rd party apps to connect to it. We would recommend you speak with the O365 Admin for granting BusyCal access to your account. In particular, we require the "EWS.AccessAsUser.All" scope to connect to your account (i.e. Exchange Web Services), and it may be that this particular permission has not been granted explicitly.
Common Trouble Shooting
The only two reasons why some other 3rd party app works is:
i) The O365 admin has explicitly granted the app permission to connect, OR
ii) They're using the native Calendar sync APIs (also known as EventKit), by way of which they're able to obtain data directly from the built-in Calendar app instead of connecting to the server directly. Our apps do not use native SDKs to obtain events from the Calendar app because doing so would severely limit the app's ability to schedule meetings, manage attendees, manage delegates, manage shared calendars and perform other complex tasks. The native SDK also does not allow apps to sync private meta-data, such as tags, contacts, colors and more. Without this, our apps would be unable to offer the tremendous flexibility it otherwise is able to when using the Exchange Web Services protocol directly.
Our apps are designed to completely replace the built-in Calendar app as well as Outlook, which means it uses the same approach as aforementioned apps.
If your Office 365 account is working but you're seeing repeat authentication prompts, please see this article about Microsoft Teams Integration.
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