I'm trying to install the Remote Server Administration Tools (RSAT) through PowerShell, but Add-WindowsCapability keeps failing with error 0x80240438. Installing it through Optional Features fails too. This computer uses a proxy and may be managed through WSUS or enterprise update policies, although normal Windows Updates work. What's the recommended way to install RSAT in 2026, either online or from an offline source?
3 Answers
For an offline install, use the matching Windows Features on Demand ISO for your Windows release and install the RSAT capability packages from there. Windows 11 24H2 and 25H2 use the same Features on Demand media because 25H2 is an enablement update. This is generally the better option in an environment where WSUS or proxy rules block online capability downloads.
You can also download the appropriate offline RSAT package and run the installer silently through your deployment tool. The important part is matching the package and language to the installed Windows build; otherwise the capability installation can fail even when networking is configured correctly.
The standard PowerShell method is: `Get-WindowsCapability -Online -Name RSAT* | Add-WindowsCapability -Online`. However, error 0x80240438 means Windows can’t reach the update endpoint. A proxy can allow regular updates while still blocking Features on Demand downloads, so check the WinHTTP proxy and any update policies affecting optional components.
That’s probably the issue. I’m using a proxy, but regular Windows Update works. I’ll check whether the proxy and update policy also allow Features on Demand downloads.