There is an issue related to the deployment of packages. This is observed on Windows 10 64bit Build 1803 but might occur on other systems, too. 

After choosing the package to be imported, the error message “Error!!! Loading a Package for Signature Validation” may be shown in the “Error Details” section of the “Import Package/DD” dialog. Along with this message another “Additional Info” will be shown, e.g. “Additional Info: Exception occurred: 1 is not a supported code page. Parameter name: codepage”. An attempt to deploy this package may end with deployed status “Failed” and an additional error “The process cannot access the file [your selected package]”. 

It depends on the overall timing if the deployment will fail or not. In general, if the first click on “Deploy” does not result in a deployed package, continue to repeat clicks on this button (>10). The following conditions are useful to enhance the chances for a successful deployment: 

- Start with an empty catalog. Remove already deployed packages from the catalog. If more than one package is required, copy the packages into one folder and import/deploy them in one session. 

- Avoid long paths to the packages. Local paths are to be preferred. 

- Wait for background processes to be completed (Antivirus update, App Store update, …)