# Object detection training fails on Ultralytics HUB with polygon dataset from Roboflow

**URL:** <https://community.ultralytics.com/t/object-detection-training-fails-on-ultralytics-hub-with-polygon-dataset-from-roboflow/2272>\
**Category:** Ultraltyics Platform\
**Tags:** yolo, support\
**Created:** [October 20, 2026, 4:42am UTC](https://community.ultralytics.com/t/object-detection-training-fails-on-ultralytics-hub-with-polygon-dataset-from-roboflow/2272 "2026-10-20T04:42:42Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Syed\_Shakil\_Mahmud](https://sea1.discourse-cdn.com/flex001/user_avatar/community.ultralytics.com/syed_shakil_mahmud/32/1773_2.png) [@Syed\_Shakil\_Mahmud](https://community.ultralytics.com/u/Syed_Shakil_Mahmud)\
**Post date:** [October 20, 2026, 4:42am UTC](https://community.ultralytics.com/t/object-detection-training-fails-on-ultralytics-hub-with-polygon-dataset-from-roboflow/2272/1 "2026-10-20T04:42:42Z")

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Hi everyone,

I exported a zipper dataset from **Roboflow** using **polygon annotations** and uploaded it directly to platform.**[ultralytics.com](http://ultralytics.com)**.

Interestingly, I can successfully train **Instance Segmentation** and **Classification** models on this dataset. However, when I try to train an **Object Detection** model, i don’t find any object detection model like yolo26s.

Since polygon data inherently contains bounding box boundaries, shouldn’t the platform auto-convert polygons to bounding boxes for object detection? Why is object detection failing while segmentation works seamlessly?

Any insights or workarounds would be highly appreciated!

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**Author:** ![Javier\_Chulvi\_Bernad](https://sea1.discourse-cdn.com/flex001/user_avatar/community.ultralytics.com/javier_chulvi_bernad/32/1726_2.png) [@Javier\_Chulvi\_Bernad](https://community.ultralytics.com/u/Javier_Chulvi_Bernad)\
**Post date:** [October 20, 2026, 11:14am UTC](https://community.ultralytics.com/t/object-detection-training-fails-on-ultralytics-hub-with-polygon-dataset-from-roboflow/2272/2 "2026-10-20T11:14:39Z")

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Hi @Syed_Shakil_Mahmud, Let me study the issue and come back to you. Thanks for bringing this up!