thanos-io/thanos · error

unsupported cache type

Error message

unsupported cache type: %s

What it means

After trying MEMCACHED, IN-MEMORY, GROUPCACHE and REDIS providers, any other config.Type value hits the default branch and yields errors.Errorf("unsupported cache type: %s"). The library throws it because the cache type string must match one of the supported BucketCacheProvider constants.

Solutions

1. Set type to one of the supported values: MEMCACHED, IN-MEMORY, GROUPCACHE, REDIS (uppercase)
2. Check the error message: it echoes the offending type string for comparison
3. Confirm your Thanos version supports the type you want (check BucketCacheProvider constants)
4. Compare against examples in Thanos docs/caching_bucket.md
5. Note the switch uppercases the type, so a correct-name-but-wrong-spelling is still rejected

Example fix

// before
config:
  caches:
    chunks:
      type: inmemory   # not an exact supported constant
// after
config:
  caches:
    chunks:
      type: IN-MEMORY

var probe struct { Config struct { Caches map[string]struct{ Type string `yaml:"type"` } `yaml:"caches"` } `yaml:"config"` }
if err := yaml.Unmarshal(yamlContent, &probe); err != nil { return err }
for name, c := range probe.Config.Caches {
    switch c.Type {
    case "MEMCACHED", "IN-MEMORY", "GROUPCACHE", "REDIS":
    default:
        return fmt.Errorf("cache %q: unsupported type %q", name, c.Type)
    }
}

func supportedCacheType(t string) bool {
    switch t {
    case "MEMCACHED", "IN-MEMORY", "GROUPCACHE", "REDIS":
        return true
    }
    return false
}

cb, err := storecache.NewCachingBucketFromYaml(yamlContent, logger, reg, bucket, router)
if err != nil {
    if strings.Contains(err.Error(), "unsupported cache type") {
        return fmt.Errorf("use MEMCACHED, IN-MEMORY, GROUPCACHE or REDIS: %w", err)
    }
    return err
}

When it happens

Trigger: NewCachingBucketFromYaml given YAML whose cache config 'type' is not exactly one of MEMCACHED, IN-MEMORY, GROUPCACHE, REDIS (matching is case-sensitive via strings.ToUpper on config.Type — a misspelling or unknown provider triggers this).

Common situations: Typos like 'inmemory', 'memcache', or lowercase variants stored oddly, using a provider introduced in a newer Thanos than the one deployed, or copying config from another project (e.g. Cortex) with different type names.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• invalid reload method
• failed to parse template
• failed to execute template
• error while parsing config for request logging
• getting http client config

AI-assisted analysis of thanos-io/thanos@35b8b99117 (2026-09-07). Data as JSON: /api/errors/1a53be6ea1ee3cad. Report an issue: GitHub.

Appendix: source

Thrown at pkg/store/cache/caching_bucket_factory.go:138

		if err != nil {
			return nil, errors.Wrapf(err, "failed to create inmemory cache")
		}
	case string(GroupcacheBucketCacheProvider):
		const basePath = "/_galaxycache/"

		c, err = cache.NewGroupcache(logger, reg, backendConfig, basePath, r, bucket, cfg)
		if err != nil {
			return nil, errors.Wrap(err, "failed to create groupcache")
		}

	case string(RedisBucketCacheProvider):
		redisCache, err := cacheutil.NewRedisClient(logger, "caching-bucket", backendConfig, reg)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to create redis client")
		}
		c = cache.NewRedisCache("caching-bucket", logger, redisCache, reg)
	default:
		return nil, errors.Errorf("unsupported cache type: %s", config.Type)
	}

	// Include interactions with cache in the traces.
	c = cache.NewTracingCache(c)
	cfg.SetCacheImplementation(c)

	cb, err := NewCachingBucket(bucket, cfg, logger, reg)
	if err != nil {
		return nil, err
	}

	return cb, nil
}

var chunksMatcher = regexp.MustCompile(`^.*/chunks/\d+$`)

func isTSDBChunkFile(name string) bool { return chunksMatcher.MatchString(name) }

View on GitHub (pinned to 35b8b99117)