Set default file block behavior: registry value openinprotectedview (excel\security\fileblock)UserHKCU\software\policies\microsoft\office\16.0\excel\security\fileblock

Policy ID: L_SetDefaultFileBlockBehavior
Scope: User Configuration
Supported on: At least Windows Server 2008 R2 or Windows 7
Source: Microsoft 365 Apps / Office Administrative Templates (version 5568.1000)
Category: Microsoft Excel 2016 › Excel Options › Security › Trust Center › File Block Settings

Registry

openinprotectedview

REG_DWORDUser

HKCU\software\policies\microsoft\office\16.0\excel\security\fileblock Current key

Enabled value: Depends on the option value
Element: -

Options
Item	Stored value
Blocked files are not opened	0
Blocked files open in Protected View and can not be edited	1
Blocked files open in Protected View and can be edited	2

Apply with .reg · CMD · PowerShell

.reg

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\software\policies\microsoft\office\16.0\excel\security\fileblock]

; Options (use only one)
; Blocked files are not opened
"openinprotectedview"=dword:00000000
; Blocked files open in Protected View and can not be edited
"openinprotectedview"=dword:00000001
; Blocked files open in Protected View and can be edited
"openinprotectedview"=dword:00000002

CMD

:: Options (use only one)

:: Blocked files are not opened
reg add "HKCU\software\policies\microsoft\office\16.0\excel\security\fileblock" /v "openinprotectedview" /t REG_DWORD /d 0 /f
:: Blocked files open in Protected View and can not be edited
reg add "HKCU\software\policies\microsoft\office\16.0\excel\security\fileblock" /v "openinprotectedview" /t REG_DWORD /d 1 /f
:: Blocked files open in Protected View and can be edited
reg add "HKCU\software\policies\microsoft\office\16.0\excel\security\fileblock" /v "openinprotectedview" /t REG_DWORD /d 2 /f

PowerShell

# Common: create the key
New-Item -Path 'HKCU:\software\policies\microsoft\office\16.0\excel\security\fileblock' -Force | Out-Null

# Options (use only one)
# Blocked files are not opened
New-ItemProperty -Path 'HKCU:\software\policies\microsoft\office\16.0\excel\security\fileblock' -Name 'openinprotectedview' -PropertyType DWord -Value 0 -Force | Out-Null
# Blocked files open in Protected View and can not be edited
New-ItemProperty -Path 'HKCU:\software\policies\microsoft\office\16.0\excel\security\fileblock' -Name 'openinprotectedview' -PropertyType DWord -Value 1 -Force | Out-Null
# Blocked files open in Protected View and can be edited
New-ItemProperty -Path 'HKCU:\software\policies\microsoft\office\16.0\excel\security\fileblock' -Name 'openinprotectedview' -PropertyType DWord -Value 2 -Force | Out-Null