Add the AbpExposeHeaders extension method.

framework/src/Volo.Abp.AspNetCore/Microsoft/AspNetCore/Cors/AbpCorsPolicyBuilderExtensions.cs

@@ -0,0 +1,12 @@
+using Microsoft.AspNetCore.Cors.Infrastructure;
+
+namespace Microsoft.AspNetCore.Cors
+{
+    public static class AbpCorsPolicyBuilderExtensions
+    {
+        public static CorsPolicyBuilder WithAbpExposeHeaders(this CorsPolicyBuilder corsPolicyBuilder)
+        {
+            return corsPolicyBuilder.WithExposedHeaders("_AbpErrorFormat");
+        }
+    }
+}

framework/src/Volo.Abp.AspNetCore/Volo.Abp.AspNetCore.csproj

@@ -32,6 +32,7 @@
     <PackageReference Include="Microsoft.AspNetCore.Http" Version="2.2.2" />
     <PackageReference Include="Microsoft.AspNetCore.StaticFiles" Version="2.2.0" />
     <PackageReference Include="Microsoft.AspNetCore.Localization" Version="2.2.0" />
+    <PackageReference Include="Microsoft.AspNetCore.Cors" Version="2.2.0" />
   </ItemGroup>
 
 </Project>