AlistGo/alist · error

unsupported meta_format: %s

Error message

unsupported meta_format: %s

What it means

Configuration validation error from Chunker.validateOptions, called during storage initialization. The meta_format option controls how chunk metadata sidecar files are serialized; only simplejson (JSON metadata files) and none (no metadata, chunk-name-only reconstruction) are implemented. Any other value is rejected before the storage comes online.

Source

Thrown at drivers/chunker/util.go:36

	"github.com/alist-org/alist/v3/internal/fs"
	"github.com/alist-org/alist/v3/internal/model"
	"github.com/alist-org/alist/v3/internal/op"
	"github.com/alist-org/alist/v3/internal/stream"
	"github.com/alist-org/alist/v3/pkg/http_range"
	"github.com/alist-org/alist/v3/pkg/utils"
)

func (d *Chunker) validateOptions() error {
	if strings.TrimSpace(d.RemotePath) == "" {
		return errors.New("remote_path is required")
	}
	if d.ChunkSize <= 0 {
		return errors.New("chunk_size must be positive")
	}
	switch d.MetaFormat {
	case "simplejson", "none":
	default:
		return fmt.Errorf("unsupported meta_format: %s", d.MetaFormat)
	}
	switch d.HashType {
	case "none", "md5", "sha1":
	default:
		return fmt.Errorf("unsupported hash_type: %s", d.HashType)
	}
	if d.MetaFormat == "none" && d.HashType != "none" {
		return fmt.Errorf("hash_type %q requires meta_format=simplejson", d.HashType)
	}
	return nil
}

func (d *Chunker) configuredRemotePaths() []string {
	seen := map[string]struct{}{}
	paths := make([]string, 0, 1)
	addPath := func(p string) {
		p = strings.TrimSpace(p)
		if p == "" {

View on GitHub (pinned to 843d9dc814)

Solutions

1. Set meta_format to "simplejson" (or "none" if no metadata files are wanted) exactly, lowercase, no extra whitespace
2. If metadata sidecars are desired, prefer simplejson since hash_type other than none requires it

Example fix

// before
"meta_format": "json"

// after
"meta_format": "simplejson"

var validMetaFormats = map[string]bool{"simplejson": true, "none": true}

if !validMetaFormats[strings.TrimSpace(cfg.MetaFormat)] {
    return fmt.Errorf("reject config before init: bad meta_format %q", cfg.MetaFormat)
}

func isValidMetaFormat(v string) bool {
    switch v {
    case "simplejson", "none":
        return true
    }
    return false
}

if err := storage.Init(ctx); err != nil {
    if strings.Contains(err.Error(), "unsupported meta_format") {
        // fix the field and re-init once, then give up
        cfg.MetaFormat = "simplejson"
    }
}

When it happens

Trigger: Creating or updating a Chunker storage with meta_format set to anything other than exactly "simplejson" or "none" — e.g. "json", "simple-json", "SimpleJson", or an empty string.

Common situations: Hand-editing the driver addition JSON; guessing option names from other drivers; case or spelling mistakes; upgrading from a fork that supported a different meta format value.

Related errors

• unsupported hash_type: %s
• hash_type %q requires meta_format=simplejson
• directory separator prohibited
• name token must come before chunk token
• pattern must contain one name token: {name}

AI-assisted analysis of AlistGo/alist@843d9dc814 (2026-08-15). Data as JSON: /api/errors/84263a3f82288c70. Report an issue: GitHub.