Keep getting "Bad minute" error, even though cron syntax seems correct

[remyvanlis]

Just installed a fresh installation of ubuntu, installed python, npm, pip and JupyterHub, did everything I wanted in the configs and it all just seems to work fine. However, after installing Jupyterlab_scheduler, I noticed it would always throw a "bad minute" error:

traceback: "Traceback (most recent call last):\n File \"/usr/local/lib/python3.9/dist-packages/tornado/web.py\", line 1702, in _execute\n result = method(*self.path_args, **self.path_kwargs)\n File \"/usr/local/lib/python3.9/dist-packages/tornado/web.py\", line 3173, in wrapper\n return method(self, *args, **kwargs)\n File \"/home/amuseic/.local/lib/python3.9/site-packages/jupyterlab_scheduler/handlers.py\", line 119, in post\n job.setall(schedule)\n File \"/home/amuseic/.local/lib/python3.9/site-packages/crontab.py\", line 235, in __exit__\n self.write()\n File \"/home/amuseic/.local/lib/python3.9/site-packages/crontab.py\", line 360, in write\n raise IOError(\"Program Error: {} returned {}: {}\".format(\nOSError: Program Error: /usr/bin/crontab returned 1: **b'\"/tmp/tmpfv9g75nc\":7: bad minute\\nerrors in crontab file, can\\'t install.\\n'\n"**

Even though I'm using copy-pasted syntax from Cron themselves:

No idea how to fix this myself, no idea what might be going wrong.

[remyvanlis]

Noticed something else. The error ends with a statement about a file in /tmp, which contains API calls to 127.0.0.1:8081:

But when actually trying to access this on 127.0.0.1:8081, I get a 500 internal server error after logging in. What I've actually hosted it on is 0.0.0.0, in my case 192.168.178.82:8888. This is due to the fact that I access it through nginx with some A records in my hosting service.

Could it have anything to do with me changing the default host?

[yangs0459]

It cased by
JUPYTERHUB_OAUTH_SCOPES="["access:servers!server=abc/", ""]" .

I update file jupyterlab_scheduler/handlers.py around line 118 as below:
`with CronTab(user=os.environ["USER"]) as cron:
for key, value in os.environ.items():
# cron.env[key] = value
try:
cron.env[key] = json.loads(value)
except Exception:
cron.env[key] = value

`

Then restart jupyterhub, it can success add cronjob.