ActiveSync EAS Broken in M365 Outlook

Update: This issue is fixed in Outlook Desktop Version 2402 Build 17328.20068 and higher

Ran into an issue with an update to M365 Apps where ActiveSync FolderSync breaks with connection resets on Outlook version 16.0.17126.20182.

To find out the build version in Outlook, go to File > Account

To find out the build version from a command line:

reg query HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\ClickToRun\Configuration /v ClientVersionToReport

Microsoft is investigating and has issued the following workaround: https://support.microsoft.com/en-us/office/outlook-desktop-exchange-activesync-connections-stopped-working-in-version-2401-da2dc0dd-297e-48ba-b6d9-ab18f5d522fc

The command to downgrade the M365 Apps:

cd %programfiles%\Common Files\Microsoft Shared\ClickToRun
officec2rclient.exe /update user updatetoversion=16.0.17126.20132

MSTeams Fastconnect Outlook Addin Disabled

Outlook keeps disabling the MSTeams Fastconnect addin which removes Teams meeting functionality from the Outlook Calendar view. To restore this, I used the following steps.

Launch RegEdit.exe
Navigate to HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins
Verify TeamsAddin.FastConnect exists.
Within TeamsAddin.FastConnect, verify LoadBehavior exists and is set to 3.
If LoadBehavior has a value other than 3, change it to 3 and restart Outlook.
For more details about how to troubleshoot this issue, you can refer to:
https://learn.microsoft.com/en-us/microsoftteams/teams-add-in-for-outlook#troubleshooting

If the add-in has been disabled, you can try to follow these steps to prevent it:

Launch RegEdit.exe
Go to HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Resiliency
Delete the DisabledItem if there is.

Disable Simplified Account Creation in Office 2016+

To disable the Simplified Account Creation dialog box in Outlook 2016, Outlook 2019 or Outlook for Office 36 and use the traditional account dialog box instead, follow these steps.

Important: Follow the steps in this section carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration in case problems occur.

Exit Outlook.
Start Registry Editor. To do this, use one of the following procedures, as appropriate for your version of Windows.
- Windows 10, Windows 8.1 and Windows 8: Press Windows Key + R to open the Run dialog box. Type regedit.exe, and then click OK.
- Windows 7: Click Start, type regedit.exe in the search box, and then press Enter.
In Registry Editor, locate and then click the user settings subkey in the registry:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\setup
or the group policy subkey in the registry:
HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\Office\16.0\Outlook\setup
Point to New on the Edit menu and then DWORD (32-bit) Value.
Type DisableOffice365SimplifiedAccountCreation, and then press Enter.
Right-click DisableOffice365SimplifiedAccountCreation, and then select Modify.
In the Value data box, type 1, and then click OK.
On the File menu, select Exit to exit Registry Editor.

Outlook 2021 – Minimize to System Tray

To minimize Outlook to the system tray when minimized, you can right-click on the Outlook icon on the taskbar and select Minimize to System Tray. On Windows 11, this option seemed to be missing. So to configure this behavior, the following registry modification can be made.

Note: This is for Outlook 2021 (16.0). You may need to adjust if you’re using Outlook 2019 (15.0) etc.

reg add HKCU\Software\Microsoft\Office\16.0\Outlook\Preferences /v MinToTray /t REG_DWORD /d 1

Calculate Working Days Between Two Dates in Excel

A quick tip in Excel (2010, 2013) for calculating working days between two dates.
Returns the number of whole working days between start_date and end_date. Working days exclude weekends and any dates identified in holidays. Use NETWORKDAYS to calculate employee benefits that accrue based on the number of days worked during a specific term.

[su_box title=Tip box_color=#94c051 title_color=#ffffff]To calculate whole workdays between two dates by using parameters to indicate which and how many days are weekend days, use the NETWORKDAYS.INTL function.[/su_box]

Example Screenshots

Including Holidays

To include holidays that are to not be considered a working day into this calculation, simply create a list of holiday dates to reference. Notice that in the example, May has a holiday so the number of working days is now 21.