Yesterday I ran into a classic but dangerous issue while working on an ASP.NET Core API:
👉 "A possible object cycle was detected"
At first, everything was working fine… until I introduced some additional logic on top of my existing response. Suddenly, my API started failing during JSON serialization.
After digging deeper, I realized the root cause:
❌ I was directly returning EF Core entities
❌ Navigation properties created a circular reference
❌ The serializer went into an infinite loop
The structure looked something like this:
Entity → Navigation → Entity → Navigation → 🔁
💥 Boom — Object Cycle Error!
🔍 How I resolved it:
Instead of sending the full entity graph to the frontend, I:
✔ Trimmed the entity to only required properties
✔ Broke the circular reference manually
✔ Understood the importance of separating API models from DB models
🚀 Key Learning:
This issue made one thing very clear:
DTOs are not optional — they are essential.
Using DTOs helps you:
✔ Avoid circular reference issues
✔ Keep your API responses clean and controlled
✔ Improve performance
✔ Maintain proper architecture
⚠️ Developer Tip:
If you're exposing EF entities directly in APIs, you're just one change away from breaking your system.
Think long-term. Avoid quick fixes.
💬 Have you ever faced this issue in your APIs?













