The app manifest publisher name must match the subject name of the signing certificate

What it means

The

Publisher

Identity

For the Microsoft Store you don't need to sign at all. Microsoft signs MSIX packages after they pass certification and replaces any signature you added. You only need this for packages you install yourself or ship outside the Store.

How to fix it

1. Confirm the cause in Event Viewer under Applications and Services Logs, Microsoft, Windows, AppxPackagingOM, Microsoft-Windows-AppxPackaging/Operational. Event 151 means the /fd hash algorithm doesn't match the package block map, so use SHA256. Event 152 means the package is corrupt and needs to be rebuilt.
2. For event 150, copy the Publisher value from your manifest and make a certificate with exactly that subject. For a test certificate:

   New-SelfSignedCertificate -Type Custom -KeyUsage DigitalSignature -CertStoreLocation "Cert:\CurrentUser\My" -TextExtension @("2.5.29.37={text}1.3.6.1.5.5.7.3.3", "2.5.29.19={text}") -Subject "CN=Contoso Software, O=Contoso Corporation, C=US" -FriendlyName "Your friendly name goes here"

3. If you use a certificate you bought, change the manifest's Publisher to the certificate's subject instead. For a Store build, keep the Publisher Partner Center gave you.
4. Sign again.