Microsoft to kill off Outlook REST API v2.0 in 2024 – for real this time

Learn to love Microsoft Graph or say hello to Mr 404

Microsoft will finally kill off the Outlook REST API v2.0 in 2024, years later than planned after the company bowed to protests from its customers and partners.

The end date is set for March 31, after which calls to the Outlook REST API and beta endpoints will throw up a 404. Following another 60 days, there will be only silence.

The company was at pains to point out that the change would not affect Outlook add-ins using Outlook REST.

Microsoft's advice is to make the jump to Microsoft Graph as soon as possible.

The Outlook REST API permits the manipulation of objects such as mail or calendar entries in Microsoft 365 and Microsoft would much rather developers used something a bit more modern instead – Microsoft Graph – and so issued a two-year warning in 2020 to the effect that the API service would be decommissioned on November 30, 2022.

Unsurprisingly, as the deadline loomed, users asked for an extension into 2023.

Microsoft blinked and moved the deadline for deprecation, which was now at an unspecified date in 2023.

Again, issues were raised.

Shifting from the Outlook REST API v2.0 to Microsoft Graph is, after all, not for the fainthearted. While the latter has pretty much caught up with the former in terms of functionality, the reams of legacy code that require updating to conform to Microsoft's latest vision are not to be underestimated.

And so the blinking went on as Microsoft and the developers and customers that depend on the service played a game of source-code chicken. Now, however, the die appears cast, and March 31, 2024, is the fateful day to pull the kill switch.

Microsoft has given plenty of notice and extended the deadline time after time. The initial two-year warning has stretched into almost twice that. The company noted: "We understand that for some applications, this change, even if anticipated, will require some work to accommodate."

So developers still clinging to what Microsoft described in 2020 as a "legacy surface area" have another date to work to. One that Microsoft seems intent on sticking to.

Unless it blinks again. ®

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