Apps are not allowed to have a Version with a revision number other than zero specified in the app manifest

What it means

A package version has four numbers. Microsoft reserves the last one, the revision, for the Store. It must be 0 when you build the package, even though the Store may change it later. Your package has something else there, like 1.0.0.1.

The other three numbers can be anything from 0 to 65535, except that the first one can't be 0. The Windows App Certification Kit checks the same rule for bundles.

How to fix it

1. Open your manifest (Package.appxmanifest in Visual Studio, or AppxManifest.xml) and find the

   Version

   attribute of the

   Identity

   element.
2. Set the last number to 0 and raise one of the first three numbers instead, like 1.0.1.0 instead of 1.0.0.1. If a packaging tool writes the version for you (electron-builder, the Flutter msix package, a CI script), change it there so the next build doesn't put it back.
3. Rebuild the package, remove the rejected one from the Packages page and upload the new one.

Does StoreFast check this?

Yes. When you drop a package on the dashboard, StoreFast reads its manifest and shows whether the version ends in .0 and is higher than the live one. The REST API, GitHub Action and MCP server refuse a version that doesn't end in .0 before anything reaches Microsoft.