Indico-celery.service failed to start - indico page is down "internal error"

Indico version 2.1.8
OS: CentOS Linux 7
Apache/2.4.6 (CentOS)

celery.log output:

2019-03-13 21:40:43,089  CRITICAL  celery.worker             Unrecoverable error: ResponseError('MISCONF Redis is configured to save RDB snapshots, but is currently not able to persist on disk. Commands that may modify the data set are disabled. Please check Redis logs for details about the error.',)
ResponseError: MISCONF Redis is configured to save RDB snapshots, but is currently not able to persist on disk. Commands that may modify the data set are disabled. Please check Redis logs for details about the error.
2019-03-14 05:02:21,436  CRITICAL  celery.worker             Unrecoverable error: ResponseError('MISCONF Redis is configured to save RDB snapshots, but is currently not able to persist on disk. Commands that may modify the data set are disabled. Please check Redis logs for details about the error.',)
ResponseError: MISCONF Redis is configured to save RDB snapshots, but is currently not able to persist on disk. Commands that may modify the data set are disabled. Please check Redis logs for details about the error.
2019-03-14 05:02:39,691  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 03:41:14,795  CRITICAL  celery.worker             Unrecoverable error: ResponseError('MISCONF Redis is configured to save RDB snapshots, but is currently not able to persist on disk. Commands that may modify the data set are disabled. Please check Redis logs for details about the error.',)
ResponseError: MISCONF Redis is configured to save RDB snapshots, but is currently not able to persist on disk. Commands that may modify the data set are disabled. Please check Redis logs for details about the error.
2019-03-19 05:01:58,218  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 05:02:04,431  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 05:02:10,315  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 05:02:16,247  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 05:02:22,448  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 05:02:28,318  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 05:02:34,267  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 05:02:40,331  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 05:02:49,091  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 05:02:56,277  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 05:03:04,441  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 05:03:12,483  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 05:03:25,611  CRITICAL  celery.worker             Unrecoverable error: OSError(12, 'Cannot allocate memory')
2019-03-19 05:03:34,164  CRITICAL  celery.worrker

–I checked redis log but there is no error

Sounds like the server is low on memory…

This server has 2GB memory and 378 MB free. I was wondering what is the minimum memory to run indico app. we just start deploying indico as proof concept and see if our department can use so, there is no a lot activities yet.

I just scaled up the server to 4GB . Indico-celery service didn’t start during reboot and and indico page is throwing error "internal server error.