asp.net Core modelstate validation is always False

asp.net Core modelstate validation is always false Environment

Win7 x64, Visual Studio 2017, Net Core 2.0 page Tips

The value ' is invalid

Describe

When a page submits a form, modelstatus.isvalid always resolves or causes the problem

The cause of this problem is that the parameters on the page and the type of the received parameter in the method are inconsistent
idea:
The parameters that the debug method receives do not see anything wrong
Since the receive parameter is no problem that must be the reason for the page assignment, by examining the assignment of the page to the parameter, the default value for the parameter is found to be null (""), and the type that receives the parameter in the method is the GUID, attempting to assign an empty GUID value to the parameter, and discovering that the current problem is not present.