cpu环境检查,FileNotFoundError: [Errno 2] No such file or directory: '/dev/null'

[cunjing56]

(paddlecpu) D:\pkg\Serving>python -m paddle_serving_server.serve check
D:\soft\anaconda3\envs\paddlecpu\lib\runpy.py:127: RuntimeWarning: 'paddle_serving_server.serve' found in sys.modules after import of package 'paddle_serving_server', but prior to execution of 'paddle_serving_server.serve'; this may result in unpredictable behaviour
warn(RuntimeWarning(msg))
Welcome to the check env shell.Type help to list commands.

(Cmd) check_all
Traceback (most recent call last):
File "D:\soft\anaconda3\envs\paddlecpu\lib\runpy.py", line 194, in _run_module_as_main
return _run_code(code, main_globals, None,
File "D:\soft\anaconda3\envs\paddlecpu\lib\runpy.py", line 87, in _run_code
exec(code, run_globals)
File "D:\soft\anaconda3\envs\paddlecpu\lib\site-packages\paddle_serving_server\serve.py", line 715, in
Check_Env_Shell().cmdloop()
File "D:\soft\anaconda3\envs\paddlecpu\lib\cmd.py", line 138, in cmdloop
stop = self.onecmd(line)
File "D:\soft\anaconda3\envs\paddlecpu\lib\cmd.py", line 217, in onecmd
return func(arg)
File "D:\soft\anaconda3\envs\paddlecpu\lib\site-packages\paddle_serving_server\serve.py", line 674, in do_check_all
check_env("all")
File "D:\soft\anaconda3\envs\paddlecpu\lib\site-packages\paddle_serving_server\env_check\run.py", line 104, in check_env
run_test_cases(inference_test_cases, "PaddlePaddle", is_open_std)
File "D:\soft\anaconda3\envs\paddlecpu\lib\site-packages\paddle_serving_server\env_check\run.py", line 63, in run_test_cases
sys.stdout = open('/dev/null', 'w')
FileNotFoundError: [Errno 2] No such file or directory: '/dev/null'

在此之前，安装包的时候报错pip install -r python/requirements.txt
ERROR: pip's dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts.
sahi 0.11.9 requires click==8.0.4, but you have click 7.1.2 which is incompatible.
sahi 0.11.9 requires opencv-python>=4.2.0.32, but you have opencv-python 3.4.17.61 which is incompatible.

我升级click就报错
ERROR: pip's dependency resolver does not currently take into account all the packages that are installed. This behaviour is the source of the following dependency conflicts.
sahi 0.11.9 requires opencv-python>=4.2.0.32, but you have opencv-python 3.4.17.61 which is incompatible.
paddle-serving-server 0.9.0 requires click==7.1.2, but you have click 8.0.4 which is incompatible.
flask 1.1.4 requires click<8.0,>=5.1, but you have click 8.0.4 which is incompatible.

请问应该怎么办？