Fix: JSON cycle detected in.NET 8 API

The Error

API returns 500:

System.Text.Json.JsonException: A possible object cycle was detected. This can either be due to a cycle or if the object depth is larger than the maximum allowed depth of 64.

Quick Fix - 30 Seconds

Your EF entities reference each other. User → Orders → User → Orders... Add this to Program.cs:

builder.Services.Configure<JsonOptions>(options =>
{
    options.JsonSerializerOptions.ReferenceHandler = ReferenceHandler.IgnoreCycles;
});

Why This Happens

EF Core creates navigation properties. User.Orders and Order.User point to each other. JSON serializer tries to follow them forever and crashes.

Best Practice for.NET 8

1. Use DTOs: Never return EF entities directly. Map to UserDto with no cycles

2. IgnoreCycles: Quick fix above. Safe for APIs

3. JsonIgnore: Add [JsonIgnore] to Order.User to break the loop

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• JSON Deserialization Fix
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