Invalid checksum for package <path>\somepackagename.nipkg
  Please check your  internet connection and try again.

• http://forums.ni.com/t5/LabVIEW/LabVIEW-NXG-1-0-installation-error-quot-Check-Internet/m-p/3635351#M1020794

1. Close NI Package Manager
2. Go to C:\ProgramData\National Instruments\NI Package Manager\Downloads\
3. Double-click on ni-labview-ng-1.0-released.nipkg and install the package
4. Double-click on ni-labview-ng-1.0-released-critical.nipkg and install the package
5. Restart NI Package Manager and try installing the package again

• http://www.ni.com/documentation/en/ni-package-manager/1.0/manual/cli-package-manager/

You can use Package Manager's command line interface (CLI) to silently install and remove NI software, build and manage packages, and view the current state of your system.

To invoke the CLI, navigate to C:\Program Files\National Instruments\NI Package Manager from the Command Prompt and then enter nipkg. The built-in help for the CLI is displayed.

You can access help for the CLI at any time by typing nipkg help. For help on a specific command, type nipkg help command.

• Available from NI Downloads Website

  • Last version to support anything but NXG5 and LV2020: NIPB 20.0
• https://forums.ni.com/t5/LabVIEW/NI-Package-Manager/td-p/3634594

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019KdtSAE&l=de-DE