Microsoft Add-in upload - "This browser is not supported in this experience. Compatible browsers include up-to-date versions of Desktop Safari, Google Chrome and Mozilla Firefox."Issue Error 'This browser is not supported in this experience. Compatible browsers include up-to-date versions of Desktop Safari, Google Chrome and Mozilla Firefox.' displayed in the Microsoft Add-in following documentation 'Upload the manifest file for a single user'CauseThe requirement to utilize this Microsoft Add-in is not met. The add-in does not support IE or Edge legacy. See also: https://docs.microsoft.com/en-us/office/dev/add-ins/concepts/browsers-used-by-office-web-add-insResolutionMicrosoft Outlook defines the web render engine used when displaying add-ins. This is something else THAN the default browser on a machine. Previously, it was IE11, then Edge Legacy, and they are now starting to support Edge Chromium by default. But when it is available, that depends on the roll-out schedule for the different Office-365 versions (bi-annual, etc) that Microsoft identified. Until Microsoft supports Edge Chromium within Outlook, this issue can occur. Requirements: - Windows: Microsoft Outlook should use; Edge Chromium and WebView2 is installed - Mac: Microsoft Outlook should use; Safari - Web: Edge Chromium, Safari, Firefox