signtool sign returns error 0x800700C1

Fri, 19 Jan 2018 17:54:49 +0000

I was trying to sign an .appx package that I created with the Desktop App Converter. However signtool returned the following error: Sign returned error: 0x800700C1 For more information, please see http://aka.ms/badexeformat

Sadly signtool doesn’t return more detailed information, even when passing the debug switch:

So what’s going on?

Sign APPX packages with PowerShell

Wed, 20 Dec 2017 15:00:33 +0000

I have been working with Microsoft’s Desktop App Converter a lot recently. Even though there’s an option to autosign the resulting package with the -Sign switch I prefer to sign APPX packages myself using signtool.

The reason is that I can send UWP packages to testers for sideloading without requiring them to import the auto generated certificate (which is different on each (re)build).

However I always forget the exact path to signtool.exe (this comes with the Windows SDK).

The Windows 10 SDK is installed by default in C:\Program Files (x86)\Windows Kits\10.

Signtool.exe will be in the folder <sdkpath>\bin\<version>\<platform>\signtool.exe.

As there are multiple version of Windows 10 there are multiple version of the SDK and you can install those concurrently.

But then I found the PowerShell cmdlet Resolve-Path which “Resolves the wildcard characters in a path, and displays the path contents”.

This does exactly what I need:

Wow, Resolve-Path is a perfect example of the many hidden gems in PowerShell!

So I decided to wrap signtool.exe in a PowerShell cmdlet as PowerShell also makes it easy to locate the correct code signing certificate from the certificate store.

SignTool on Remko's Blog

signtool sign returns error 0x800700C1

Sign APPX packages with PowerShell