Fix ChildFailedError

✅ Solution

ChildFailedError in transformers often arises from inconsistencies in distributed training setup, particularly when using Accelerate and FSDP with Trainer. Ensure that all processes have the same environment and configurations, and explicitly set `ddp_find_unused_parameters=False` in your Trainer arguments to avoid deadlocks due to unused parameters. Also, verify that all processes are synchronized properly, especially within custom training loops or callbacks where data loading or model updates may not be identical across ranks.