EWS API throws error “No Mailbox with such GUID”

Recently i was working with an ISV/application developer, who created this custom application using EWS (Exchange Web Services) API. It worked with the account with impersonation rights to access other mailboxes/calendars in Azure/Office 365/Exchange Online. But when they tried to access a specific mailbox calendar, they see the error “No mailbox with such GUID”. We…


Office Debug: Office add-ins are not displayed correctly in Outlook

Recently one of the ISV app developer reported that after they update Microsoft Outlook to version 1809 (build 10827.20181) or later versions, data from some Office add-ins may not be displayed correctly or may be missing from the user interface of the add-in within Outlook. Specifically in their case, they used IE Control hosted in…