The manifest has no XML signature

Seeing the following ClickOnce error log?  Well your ClickOnce manifests are not signed ...

System.Deployment.Application.InvalidDeploymentException (ManifestParse)
  - Exception reading manifest from https://foo.application: the manifest could be invalid or the file could not be opened.
  --- Inner Exception ---
  System.Deployment.Application.ValidationFailedException (Unknown subtype)
  - The manifest has no XML signature.

But I did sign the manifest while publishing in VS?

Check if your project includes assemblies with spaces in their name.
There is a known Beta2 bug which causes VS to barf on signing manifest if the project includes Assemblies with spaces in the name.
Renaming the Assemblies in the easy workaround.