Sorry for the late reply. The reason is
[2021-05-11 08:36:38,834 I 29410 29410] worker_pool.cc:342: Some workers of the worker process(29490) have not registered to raylet within timeout.
So the timeout happens first and the worker is removed from raylet and later on when the worker tries to register, we cannot find it anymore.
You can increase the timeout by setting RAY_worker_register_timeout_seconds environment variable.