How to debug problems with vc_redist bootstrapper?

Question

I've got a Visual Studio installer project (a vdproj) that won't install the VC redistributables as a pre-requisite. I can't figure out why.

I'm using the latest updates to Visual Studio 2019, with the Installer Projects extension. Here are my prerequisite settings:

At install time I get an error that says vc_redist.x64.exe has changed since it was initially published. I checked bootstrap at C:\Program Files (x86)\Microsoft SDKs\ClickOnce Bootstrapper\Packages\vcredist_x64 and discovered that the URL found there (https://aka.ms/vs/16/release/14.26.55555/vc_redist.x64.exe) redirects to the main microsoft home page and downloads HTML rather than an executable. So I changed the URL, first to https://aka.ms/vs/16/release/vc_redist.x64.exe, then to https://aka.ms/vs/16/release/14.27.29016/vc_redist.x64.exe. Both of these URLs download a copy of VC_redist.x64.exe when you visit them with a web browser, but neither of them fixes the installer.

The only difference I see after changing the URL is that with the original URL I get a file named vcredist_x64\vc_redist.x64.exe in the temp install folder (but it's invalid, full of HTML), but with the two new URLs the vcredist_x64 folder is empty.

Any idea what I need to do to get this working?

Answer 1

I found the solution. I needed change the URL and the public key. Here are the steps you would follow to resolve an issue like this in the future:

1. Find the URL to a version that is still available. The latest version is currently available from here: https://aka.ms/vs/16/release/vc_redist.x64.exe. The version-specific URL to that same file is currently http://aka.ms/vs/16/release/14.27.29016/vc_redist.x64.exe.
2. Note the version number. If you don't already know it, you can get it by simply hovering over the downloaded file in file explorer.
3. Find the public key. I learned how to do that from an answer in this question. You find the key by right-clicking on vc_redist.x64.exe, selecting properties, Digital Signatures, then double-click on the sha1 entry. Click View Certificate, then Details, then Public key. Copy the value that shows up in the text box.
4. Remove all the spaces from the public key you copied. The public key for v14.27.29016 of vc_redist.x64.exe is: 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
5. Open C:\Program Files (x86)\Microsoft SDKs\ClickOnce Bootstrapper\Packages\vcredist_x64\product.xml in a text editor, as administrator.
6. Replace the value of the PublicKey with the key you prepared in step 4.
7. In the BypassIf element, replace the Value with the version you noted in step 2. Save and close the file.
8. Open C:\Program Files (x86)\Microsoft SDKs\ClickOnce Bootstrapper\Packages\vcredist_x64\en\package.xml in a text editor, as admin.
9. Replace VCRedistExe with the URL from step 1. You can use either the generic or the version-specific URL. They both have drawbacks. Save and close the file.
10. Rebuild your installer.

You may need to make adjustments for your environment.

Regarding the choice of URL, I suspect neither will work forever. If you use a version-specific URL, that version might go away (which is the whole reason we're needing to mess with this in the first place). If you use the version-agnostic URL, then when a new version comes out the product key probably won't match.

It's really unfortunate that Microsoft makes existing installers break by taking old redist packages down, and doesn't provide the updates required for new installers to work out of the box.