NanmiCoder/MediaCrawler · error · ValueError

Unknown cache type: {cache_type}

Error message

Unknown cache type: {cache_type}

What it means

ValueError from CacheFactory.create_cache when cache_type is neither 'memory' nor 'redis'. The factory lazily imports ExpiringLocalCache for 'memory' and RedisCache for 'redis', and treats any other string as a programming/configuration error.

Source

Thrown at cache/cache_factory.py:49

    """

    @staticmethod
    def create_cache(cache_type: str, *args, **kwargs):
        """
        Create cache object
        :param cache_type: Cache type
        :param args: Arguments
        :param kwargs: Keyword arguments
        :return:
        """
        if cache_type == 'memory':
            from .local_cache import ExpiringLocalCache
            return ExpiringLocalCache(*args, **kwargs)
        elif cache_type == 'redis':
            from .redis_cache import RedisCache
            return RedisCache()
        else:
            raise ValueError(f'Unknown cache type: {cache_type}')

View on GitHub (pinned to d6f7c5bb90)

Solutions

1. Set cache_type to exactly 'memory' or 'redis' (lowercase) in config/base_config.py or wherever create_cache is called.
2. If you need a new backend, add an elif branch mapping your type to its class before relying on it.
3. Log the incoming cache_type at startup so typos surface immediately.

Example fix

# before
CacheFactory.create_cache('mem')

# after
CacheFactory.create_cache('memory')

from cache.cache_factory import CacheFactory
SUPPORTED = {'memory', 'redis'}
if cache_type not in SUPPORTED:
    raise SystemExit(f'cache type must be one of {sorted(SUPPORTED)}, got {cache_type!r}')
cache = CacheFactory.create_cache(cache_type)

def is_supported_cache(t: str) -> bool:
    return isinstance(t, str) and t in {'memory', 'redis'}

try:
    cache = CacheFactory.create_cache(cfg.CACHETYPE_STRING)
except ValueError:
    logger.error('bad cache type; defaulting to memory')
    cache = CacheFactory.create_cache('memory')

When it happens

Trigger: Passing cache_type from config (e.g. CACHETYPE_STRING) with a typo like 'Memory', 'mem', 'local', or an empty string; adding a new cache backend (e.g. 'memcached') without extending the factory's if/elif chain.

Common situations: Editing the config file's cache type value; case mismatch between documented values and the code's exact lowercase literals; upgrading/downgrading versions where supported cache types changed.

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AI-assisted analysis of NanmiCoder/MediaCrawler@d6f7c5bb90 (2026-08-15). Data as JSON: /api/errors/4e3f456ff3ed1d70. Report an issue: GitHub.