Repeated server error 500 after 013.1 upgrade

Support Kolibri
1

Following a successful upgrade to v 0.13.1 yesterday, we now have consistent Server 500 errors. The record of the error that repeats with each server crash is below. It’s the same error that recurs each time. Is there a fix that I can implement? Kolibri cannot run for very long after each restart with this error.

ERROR 2020-02-17 09:08:49,530 exception Internal Server Error: /api/content/contentnode_slim/
Traceback (most recent call last):
File “/usr/lib/python3/dist-packages/kolibri/dist/django/core/handlers/exception.py”, line 41, in inner
response = get_response(request)
File “/usr/lib/python3/dist-packages/kolibri/dist/django/utils/deprecation.py”, line 142, in call
response = self.process_response(request, response)
File “/usr/lib/python3/dist-packages/kolibri/dist/django/middleware/cache.py”, line 99, in process_response
cache_key = learn_cache_key(request, response, timeout, self.key_prefix, cache=self.cache)
File “/usr/lib/python3/dist-packages/kolibri/dist/django/utils/cache.py”, line 402, in learn_cache_key
cache.set(cache_key, headerlist, cache_timeout)
File “/usr/lib/python3/dist-packages/kolibri/dist/redis_cache/backends/base.py”, line 30, in wrapped
return method(self, client, key, *args, **kwargs)
File “/usr/lib/python3/dist-packages/kolibri/dist/redis_cache/backends/base.py”, line 274, in set
result = self._set(client, key, self.prep_value(value), timeout, _add_only=False)
File “/usr/lib/python3/dist-packages/kolibri/dist/redis_cache/backends/base.py”, line 267, in _set
return client.set(key, value, nx=_add_only, ex=timeout)
File “/usr/lib/python3/dist-packages/kolibri/dist/redis/client.py”, line 1451, in set
return self.execute_command(‘SET’, *pieces)
File “/usr/lib/python3/dist-packages/kolibri/dist/redis/client.py”, line 775, in execute_command
return self.parse_response(connection, command_name, **options)
File “/usr/lib/python3/dist-packages/kolibri/dist/redis/client.py”, line 789, in parse_response
response = connection.read_response()
File “/usr/lib/python3/dist-packages/kolibri/dist/redis/connection.py”, line 642, in read_response
raise response
redis.exceptions.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.
INFO 2020-02-17 09:10:39,237 system Initiating shutdown of Kolibri

2

Hello Chris, the error dump you pasted here indicates there’s an error in the service used for caching: redis. It’s not a kolibri error itself.
It seems some of the redis files have now wrong permissions and can’t be written. The redis log can provide more information to know where the problem is exactly, please, can you attach it here? it’s the file /var/log/redis/redis-server.log in your server.

In the meantime, while this problem is solved, you can disable this kind of caching, in the file options.ini placed in your .kolibri folder you’ll have these two lines:

[Cache]
CACHE_BACKEND = redis

You can edit this file adding a # in front of the line with the CACHE_BACKEND text. This will tell kolibri not to use redis for caching. The application performance will be a bit worse but kolibri will work having this service down.