---
description: Improve YOLOv5 model training with Ultralytics' on-train callbacks. Boost performance on-pretrain-routine-end, model-save, train/predict start.
keywords: Ultralytics, YOLO, callbacks, on_pretrain_routine_end, on_fit_epoch_end, on_train_start, on_val_start, on_predict_start, on_export_start
---
# on_pretrain_routine_end
---
:::ultralytics.yolo.utils.callbacks.hub.on_pretrain_routine_end
< br > < br >
# on_fit_epoch_end
---
:::ultralytics.yolo.utils.callbacks.hub.on_fit_epoch_end
< br > < br >
# on_model_save
---
:::ultralytics.yolo.utils.callbacks.hub.on_model_save
< br > < br >
# on_train_end
---
:::ultralytics.yolo.utils.callbacks.hub.on_train_end
< br > < br >
# on_train_start
---
:::ultralytics.yolo.utils.callbacks.hub.on_train_start
< br > < br >
# on_val_start
---
:::ultralytics.yolo.utils.callbacks.hub.on_val_start
< br > < br >
# on_predict_start
---
:::ultralytics.yolo.utils.callbacks.hub.on_predict_start
< br > < br >
# on_export_start
---
:::ultralytics.yolo.utils.callbacks.hub.on_export_start
< br > < br >
