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For the same calendar event fetching the ID in Outlook JS and getting the it from MS Graph API returns slightly different strings: Notice that they differ only in the separator strings

+ is swapped with _ / is swapped with -

Outlook JS: AAMkAGUwYzI4OGZmLWY3YzAtNDNkMC04ZDljLTczZmJjMzM3Y2Y3ZgBGAAAAAAC0gTCu+FfeT5pt2ms+2dYpBwDXTgLnaOKqSLvwJ5eRN/89AAAAAAENAADXTgLnaOKqSLvwJ5eRN/89AAB94CiRAAA=

Graph API: AAMkAGUwYzI4OGZmLWY3YzAtNDNkMC04ZDljLTczZmJjMzM3Y2Y3ZgBGAAAAAAC0gTCu_FfeT5pt2ms_2dYpBwDXTgLnaOKqSLvwJ5eRN-89AAAAAAENAADXTgLnaOKqSLvwJ5eRN-89AAB94CiRAAA=

Your Environment

Platform [PC desktop, Mac, iOS, Office on the web]: PC desktop and Office on the web
Host [Excel, Word, PowerPoint, etc.]: Outlook
Office version number: Microsoft Outlook Version 1.2024.708.200 (Office 365)
Operating System: Windows 11 Enterprise Version 23H2 OS Build 22631.3880
Browser (if using Office on the web): Microsoft Edge for Business Version 126.0.2592.102 (Official build) (64-bit)

Expected behavior

The ID string is case sensitive and should not differ in any character regardless of platform

Current behavior

The ID string is case sensitive but differ in special characters based on platform

Steps to reproduce

Outlook JS in web

await Office.onReady();
const item = Office.context.mailbox.item;
return item.itemId;

Outlook JS in desktop

 const itemIdPromise = new Promise((resolve, reject) => {
     Office.context.mailbox.item.getItemIdAsync((result) => {
         if (result.status === Office.AsyncResultStatus.Succeeded) {
             resolve(result.value);
         } else {
             reject(result.error.message);
         }
     });
 });

Graph API

HTTP GET https://graph.microsoft.com/v1.0/me/events

Link to live example(s)

https://developer.microsoft.com/en-us/graph/graph-explorer

Provide additional details

Context

I need to Create an item in the database with the ID using Outlook JS, and at the same time I am subscribing to Outlook Calendar event change notifications by Graph API and I create also save the items to the database. Duplication detection is needed, thus I need to trust the ID is unique

Useful logs

https://github.com/ystvan/OutlookRepro Added @exextoc as a collaborator

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OfficeDev / office-js

Outlook Calendar Appointment unique ID is different in Office JS and Graph API #4729