Validation - Do not write validation exceptions to the application log file

Starting with v15.2.8 it will be easier for you to override the Tracing class behavior with the new CreateCustomTracer  event and virtual methods of the Tracing class.

See Also:
Concepts > Debugging and Error Handling > Add Custom Log Entries and Customize the Default Tracer Behavior
Tracing - How to exclude loaded assemblies from the eXpressAppFramework.log file
How to replace XAF exception handling with Logify

It would be satisfying if DevExpress only made the following methods virtual:
- Tracing.LogError(Exception exception)
- Tracing.LogError(string text, params object[] args)
- Tracing.LogLoadedAssemblies()
Then, the following class could be used:

C#
public class CustomTracing : Tracing  
{  
    public static void InjectTracer()  
    {  
        FieldInfo field = typeof(Tracing).GetField("tracer", BindingFlags.Static | BindingFlags.NonPublic);  
        field.SetValue(null, new CustomTracing());  
    }  

    public override void LogError(Exception exception)  
    {  
        if (!(exception is ValidationException))  
            base.LogError(exception);  
    }  
    public override void LogError(string text, params object[] args)  
    {  
        if (!text.Contains("    Type:       ValidationException"))  
        {  
            int ind = text.LastIndexOf("Loaded assemblies");  
            if (ind != -1)  
                text = text.Substring(0, ind);  
            base.LogError(text, args);  
        }  
    }  
    public override void LogLoadedAssemblies() { /* base.LogLoadedAssemblies();*/ }  
}  

…and initialisation of the mechanism:

C#
public sealed partial class YourApplicationModule : ModuleBase  
{  
    ...  
    public override void Setup(XafApplication application)  
    {  
        CustomTracing.InjectTracer();  
        base.Setup(application);  
    }  
}