Error 0x800B0100 - App Package Must Be Digitally Signed

Hello Suraj Kamya. Thanks for the details and the screenshots.

The 0x800B0100 from WACK means the bundle you tested wasn’t signed with a certificate that Windows trusts on your machine. Store association sets identity, but you still need a trusted cert on the package you run through WACK.

What to do (choose the path you’re using):

• For Microsoft Store submission
  • Visual Studio → Project → Store → Associate App with the Store (pick the exact app).
  • Project → Store → Create App Packages → “I want to create packages for the Microsoft Store.”
  • Ensure the wizard shows a Store signing certificate (avoid “Create test certificate” here).
  • Build and let WACK run on the produced bundle.
• For sideload/local testing
  • Create App Packages → “Sideloading.”
  • Choose/Create a test or enterprise certificate.
  • Install the certificate chain so the machine trusts it:
    • Root and any intermediates → Local Computer → Trusted Root / Intermediate Certification Authorities
    • Leaf certificate → Current User → Trusted People
  • Rebuild the bundle and verify:
    • signtool verify /pa "YourApp_x64.appxbundle"

Quick checks

• Package.appxmanifest → Packaging → Publisher must exactly match the Partner Center publisher subject.
• If the packaging dialog shows “Sign packages using: None,” select the Store cert (Store path) or your test/enterprise cert (sideload path).
• Clear stale bits: close VS, delete bin/ and obj/, re‑associate, rebuild, repackage.

If it still fails, share the signtool verify /pa output and the failing section of the WACK XML, and the Publisher line from your Package.appxmanifest.

Hope this helps you get past the error!

Thanks Suraj Kamya for the extra screenshot.

That dialog (“Create App Packages”) showing only:

• Microsoft Store under a new app name
• Sideloading

Means Visual Studio does not consider this project associated with an existing Store app. When association is valid, you’ll see a plain “Microsoft Store” option with the reserved app name prefilled. So either the association never stuck, or it’s for a different project/folder than the one you’re packaging.

What to check and do next:

• Open the exact UWP project you’re packaging (not a class library). Then check the project root for Package.StoreAssociation.xml. If it’s missing, association isn’t in effect.
• If the file exists, open it and confirm the AppName/Publisher match your Partner Center app. If they don’t, re‑associate.
• Unity export note: exporting UWP again can overwrite the VS project and remove Package.StoreAssociation.xml. Re‑associate after every fresh Unity export.
• Try a clean re‑association:
  • Close VS, delete bin/ and obj/ folders.
  • Delete Package.StoreAssociation.xml if present.
  • Reopen the project → Project → Store → Associate App with the Store… → select the exact app (you must be signed in to the same Partner Center account where the name is reserved).
  • Now run Project → Store → Create App Packages… — you should see “Microsoft Store” (not “under a new app name”).
• Make sure you’re invoking the wizard on the UWP project node, not on the solution or another project type.
• If you truly intend to sideload, pick “Sideloading,” then ensure you select/create a certificate and install its chain so WACK can validate the signature (otherwise you’ll keep getting 0x800B0100).

Once the wizard shows “Microsoft Store,” build the package and let WACK run; that output will be correctly signed for validation.

If it still only shows “under a new app name,” please share whether Package.StoreAssociation.xml exists and a redacted snippet of its Publisher and AppDisplayName, and confirm whether the Unity re‑export happened right before packaging.

Hope this points you to the fix.

Yes I am associating app from UWP node as shown in highlighted screenshot.. Even after association there is no such file named "Package.StoreAssociation.xml"

I tired deleting and clean build 6-7 times already but still same issue!

Your wizard only shows “Microsoft Store under a new app name” and “Sideloading,” and there’s no Package.StoreAssociation.xml in the project. That means the association didn’t stick for this UWP project.

Try this to make it stick:

• Check the account: in Visual Studio, sign in with the same Partner Center account that owns the app. Then run Project → Store → Associate App with the Store… and pick the exact app.
• Make sure the project folder is writable: close VS, remove Read‑only on the project directory, and delete bin, obj, and .vs. Reopen VS on the UWP project node (not the solution) and associate again.
• Unity note: if you re‑export from Unity, it can overwrite the VS project and drop the association file. Associate again after any fresh export.
• Confirm the file: after the “association was successful” message, you should see Package.StoreAssociation.xml in the project root (use “Show All Files” to spot it).
• If it still won’t appear, download the association file from Partner Center (App management → App identity), place it in the project root as Package.StoreAssociation.xml, then reload the project.

Once the association is really in place, the packaging wizard will show a plain “Microsoft Store” option (not “under a new app name”). Build from there and WACK should be able to validate the signature.

I’ve reviewed and verified all the steps, but the Package.StoreAssociation.xml file is still not appearing.

Could you please guide me on how to download this file? On the Product Identity page under Product Management, I can see all the app information and IDs, but there doesn’t seem to be an option to download the file. Alternatively, is there a template available that I can fill in manually?

Also, just to confirm—should this file be placed at the same level as the .sln file?