What it does
If this policy is enabled, you can use JSON to configure default application handlers. If this policy is disabled or not configured, Firefox defaults are used. For detailed information on creating the policy, see https://firefox-admin-docs.mozilla.org/reference/policies/handlers/.
What it writes
- Hive
- HKEY_LOCAL_MACHINE or HKEY_CURRENT_USER
- Registry key
Software\Policies\Mozilla\Firefox
Options
| Option | Type | Registry value | Allowed values |
|---|---|---|---|
| JSONOneLine | Text | Handlers |
Up to 16384 characters |
Configure and deploy
Choose a state and the option values; the output below is generated from the template for exactly that.
Enabled · Computer · template defaults
Registry file (.reg)
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\Software\Policies\Mozilla\Firefox]
"Handlers"=""
PowerShell
$ErrorActionPreference = 'Stop'
function Set-RegistryValue {
param(
[Parameter(Mandatory = $true)][string] $Path,
[Parameter(Mandatory = $true)][string] $Name,
[Parameter(Mandatory = $true)][string] $PropertyType,
[Parameter(Mandatory = $true)][object] $Value
)
if (-not (Test-Path -LiteralPath $Path)) {
New-Item -Path $Path -Force | Out-Null
}
New-ItemProperty -LiteralPath $Path -Name $Name -PropertyType $PropertyType -Value $Value -Force | Out-Null
}
function Remove-RegistryValue {
param(
[Parameter(Mandatory = $true)][string] $Path,
[Parameter(Mandatory = $true)][string] $Name
)
if (Test-Path -LiteralPath $Path) {
Remove-ItemProperty -LiteralPath $Path -Name $Name -Force -ErrorAction SilentlyContinue
}
}
function Clear-RegistryKeyValues {
param(
[Parameter(Mandatory = $true)][string] $Path
)
if (-not (Test-Path -LiteralPath $Path)) {
return
}
foreach ($propertyName in (Get-Item -LiteralPath $Path).Property) {
Remove-ItemProperty -LiteralPath $Path -Name $propertyName -Force -ErrorAction SilentlyContinue
}
}
# Policy: Handlers (JSON on one line)
# Name: HandlersOneLine
# Scope: Machine
# State: Enabled
# Source: firefox.admx
Set-RegistryValue -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Mozilla\Firefox' -Name 'Handlers' -PropertyType 'String' -Value ''
- The OMA-URI is an inferred ADMX-backed Policy CSP candidate derived from the source ADMX file name and policy name.
- Some Microsoft policies use built-in Policy CSP pages whose area names don't match the ADMX file name, so verify the candidate against Microsoft Learn before deployment.
- The generated payload is incomplete because one or more ADMX element values were not supplied: JSONOneLine
ADMX profile candidate (OMA-URI)
./Device/Vendor/MSFT/Policy/Config/ADMX_firefox/HandlersOneLineIntune remediation scripts
Detection
$ErrorActionPreference = 'Stop'
$reasons = [System.Collections.Generic.List[string]]::new()
function Test-RegistryValueExists {
param(
[Parameter(Mandatory = $true)][string] $Path,
[Parameter(Mandatory = $true)][string] $Name
)
if (-not (Test-Path -LiteralPath $Path)) {
return $false
}
return $null -ne (Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction SilentlyContinue)
}
function Test-RegistryValueEquals {
param(
[Parameter(Mandatory = $true)][string] $Path,
[Parameter(Mandatory = $true)][string] $Name,
[Parameter(Mandatory = $true)][string] $Kind,
[Parameter(Mandatory = $true)][object] $Expected
)
if (-not (Test-Path -LiteralPath $Path)) {
return $false
}
$valueObject = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction SilentlyContinue
if ($null -eq $valueObject) {
return $false
}
$actual = $valueObject.$Name
switch ($Kind) {
'String' { return [string]$actual -ceq [string]$Expected }
'ExpandString' { return [string]$actual -ceq [string]$Expected }
'DWord' { return [uint32]$actual -eq [uint32]$Expected }
'QWord' { return [uint64]$actual -eq [uint64]$Expected }
'MultiString' {
$actualArray = @($actual)
$expectedArray = @($Expected)
if ($actualArray.Count -ne $expectedArray.Count) { return $false }
for ($index = 0; $index -lt $actualArray.Count; $index++) {
if ([string]$actualArray[$index] -cne [string]$expectedArray[$index]) { return $false }
}
return $true
}
'Binary' {
$actualArray = [byte[]]$actual
$expectedArray = [byte[]]$Expected
if ($actualArray.Length -ne $expectedArray.Length) { return $false }
for ($index = 0; $index -lt $actualArray.Length; $index++) {
if ($actualArray[$index] -ne $expectedArray[$index]) { return $false }
}
return $true
}
default { return [string]$actual -ceq [string]$Expected }
}
}
# Policy: Handlers (JSON on one line)
# Name: HandlersOneLine
# Scope: Machine
# State: Enabled
# Source: firefox.admx
$isMatch = Test-RegistryValueEquals -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Mozilla\Firefox' -Name 'Handlers' -Kind 'String' -Expected ''
if (-not $isMatch) {
$reasons.Add('Value mismatch: HKEY_LOCAL_MACHINE\Software\Policies\Mozilla\Firefox\Handlers') | Out-Null
}
if ($reasons.Count -eq 0) {
Write-Output 'Compliant'
exit 0
}
$reasons | ForEach-Object { Write-Output $_ }
exit 1
Remediation
$ErrorActionPreference = 'Stop'
function Set-RegistryValue {
param(
[Parameter(Mandatory = $true)][string] $Path,
[Parameter(Mandatory = $true)][string] $Name,
[Parameter(Mandatory = $true)][string] $PropertyType,
[Parameter(Mandatory = $true)][object] $Value
)
if (-not (Test-Path -LiteralPath $Path)) {
New-Item -Path $Path -Force | Out-Null
}
New-ItemProperty -LiteralPath $Path -Name $Name -PropertyType $PropertyType -Value $Value -Force | Out-Null
}
function Remove-RegistryValue {
param(
[Parameter(Mandatory = $true)][string] $Path,
[Parameter(Mandatory = $true)][string] $Name
)
if (Test-Path -LiteralPath $Path) {
Remove-ItemProperty -LiteralPath $Path -Name $Name -Force -ErrorAction SilentlyContinue
}
}
function Clear-RegistryKeyValues {
param(
[Parameter(Mandatory = $true)][string] $Path
)
if (-not (Test-Path -LiteralPath $Path)) {
return
}
foreach ($propertyName in (Get-Item -LiteralPath $Path).Property) {
Remove-ItemProperty -LiteralPath $Path -Name $propertyName -Force -ErrorAction SilentlyContinue
}
}
# Policy: Handlers (JSON on one line)
# Name: HandlersOneLine
# Scope: Machine
# State: Enabled
# Source: firefox.admx
Set-RegistryValue -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Mozilla\Firefox' -Name 'Handlers' -PropertyType 'String' -Value ''
History 93 retained releases
- 8.120 Aug 2026
- Description
… Firefox defaults are used.
For detailed information on creating the policy, see
[removed: https://github.com/mozilla/policy-templates/blob/master/README.md#handlers.][added: https://firefox-admin-docs.mozilla.org/reference/policies/handlers/.]Whole description, marked
If this policy is enabled, you can use JSON to configure default application handlers. If this policy is disabled or not configured, Firefox defaults are used. For detailed information on creating the policy, see
[removed: https://github.com/mozilla/policy-templates/blob/master/README.md#handlers.][added: https://firefox-admin-docs.mozilla.org/reference/policies/handlers/.]
- Description
… Firefox defaults are used.
For detailed information on creating the policy, see
- 6.1028 Apr 2025
- Translations changed; choose a language above to compare its wording.
- 6.69 Jan 2025
- Translations changed; choose a language above to compare its wording.
- 6.526 Nov 2024
- Translations changed; choose a language above to compare its wording.
- 6.011 Jul 2024
- Translations changed; choose a language above to compare its wording.
- 5.229 Aug 2023
- Added in this release.
36 later releases left it unchanged.
Template
- Internal name
HandlersOneLine- Namespace
Mozilla.Policies.Firefox- Template file
firefox.admx- Release
- Mozilla Firefox 8.4 · file set
a495190075c2a974…
Definition, editor controls and support
Definition
<policy class="Both" displayName="$(string.HandlersOneLine)" explainText="$(string.Handlers_Explain)" key="Software\Policies\Mozilla\Firefox" name="HandlersOneLine" presentation="$(presentation.JSONOneLine)" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
<parentCategory ref="Mozilla.Policies.Firefox:firefox" />
<supportedOn ref="Mozilla.Policies.Firefox:SUPPORTED_FF78" />
<elements>
<text id="JSONOneLine" maxLength="16384" valueName="Handlers" />
</elements>
</policy>Editor controls
<presentation id="JSONOneLine" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
<textBox refId="JSONOneLine">
<label />
</textBox>
</presentation>Supported platforms and category
Mozilla.Policies.Firefox:category:firefox
<category displayName="$(string.firefox)" name="firefox" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
<parentCategory ref="Mozilla.Policies:Cat_Mozilla" />
</category>
Mozilla.Policies.Firefox:definition:SUPPORTED_FF78
<definition displayName="$(string.SUPPORTED_FF78)" name="SUPPORTED_FF78" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
Mozilla.Policies:category:Cat_Mozilla
<category displayName="$(string.mozilla)" name="Cat_Mozilla" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
Mozilla.Policies.Firefox:category:firefox
<category displayName="$(string.firefox)" name="firefox" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
<parentCategory ref="Mozilla.Policies:Cat_Mozilla" />
</category>
<strings><string id="Mozilla.Policies.Firefox:firefox">Firefox</string></strings>
Mozilla.Policies.Firefox:definition:SUPPORTED_FF78
<definition displayName="$(string.SUPPORTED_FF78)" name="SUPPORTED_FF78" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
<strings><string id="Mozilla.Policies.Firefox:SUPPORTED_FF78">Firefox 78 or later</string></strings>
Mozilla.Policies:category:Cat_Mozilla
<category displayName="$(string.mozilla)" name="Cat_Mozilla" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
<strings><string id="Mozilla.Policies:mozilla">Mozilla</string></strings>