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Non-nullable property must contain a non-null value when exiting constructor. Consider declaring the property as nullable

ayi

<t>Non-nullable property must contain a non-null value when exiting constructor. Consider declaring the property as nullable</t>

ayi

<t>The compiler is warning you that the default assignment of your string property (which is null) doesn't match its stated type (which is non-null string). 
 
This is emitted when nullable reference types are switched on, which changes all reference types to be non-null, unless stated otherwise with a ?. 
 
For example, your code could be changed to

public class Greeting<br/>
{<br/>
    public string? From { get; set; }<br/>
    public string? To { get; set; } <br/>
    public string? Message { get; set; }<br/>
}<br/>
<br/>
```<br/>
<br/>
to declare the properties as nullable strings, or you could give the properties defaults in-line or in the constructor:<br/>
<br/>
```<br/>
public class Greeting<br/>
{<br/>
    public string From { get; set; } = string.Empty;<br/>
    public string To { get; set; } = string.Empty;<br/>
    public string Message { get; set; } = string.Empty;<br/>
}<br/>
<br/>
```<br/>
<br/>
if you wish to retain the properties' types as non-null.</t>