What causes "failed to get download link" in AlistGo/alist?

Check the actual status: temporarily log ar.StatusCode before the guard to identify 401/403/400

failed to get download link

Error message

failed to get download link

What it means

In Link() with WebProxy enabled, the driver probes the Feishu download endpoint with a 'Range: bytes=0-1' request and expects 206 Partial Content as proof the URL+Bearer token yield a working download. Any other status after the one retry-with-forced-refresh falls here. It is a link-validation failure: the returned model.Link would be broken, so none is returned.

Source

Thrown at drivers/lark/driver.go:407

			return nil, err
		}
		_ = ar.Body.Close()

		if isHTTPAuthFailed(ar.StatusCode) && strings.TrimSpace(c.RefreshToken) != "" {
			accessToken, err = c.downloadAccessToken(ctx, true)
			if err != nil {
				return nil, err
			}
			req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", accessToken))
			ar, err = http.DefaultClient.Do(req)
			if err != nil {
				return nil, err
			}
			_ = ar.Body.Close()
		}

		if ar.StatusCode != http.StatusPartialContent {
			return nil, errors.New("failed to get download link")
		}

		return &model.Link{
			URL: url,
			Header: http.Header{
				"Authorization": []string{fmt.Sprintf("Bearer %s", accessToken)},
			},
		}, nil
	}

	return nil, errors.New("lark download requires web proxy")
}

func (c *Lark) filePreviewURL(token string) string {
	prefix := strings.TrimRight(strings.TrimSpace(c.TenantUrlPrefix), "/")
	if prefix == "" {
		prefix = "https://www.feishu.cn"
	}

View on GitHub (pinned to 843d9dc814)

Solutions

Check the actual status: temporarily log ar.StatusCode before the guard to identify 401/403/400
For native doc types, use the export flow (createExportTask) instead of direct download
Re-grant app/user permissions (drive:file:download scope) and refresh tokens
Ensure the token used is a user access token with access to that specific file

Example fix

// before
if ar.StatusCode != http.StatusPartialContent {
	return nil, errors.New("failed to get download link")
}
// after (diagnosable failure)
if ar.StatusCode != http.StatusPartialContent {
	return nil, fmt.Errorf("failed to get download link: probe status=%d", ar.StatusCode)
}

Defensive patterns

Strategy: try-catch

Validate before calling

if !c.WebProxy {
	return nil, errors.New("enable web proxy on the lark storage to download files")
}

Try / catch

link, err := c.Link(ctx, file, args)
if err != nil && err.Error() == "failed to get download link" {
	// probe failed (401/403/400): check permission and file type, then surface clearly
	return nil, fmt.Errorf("feishu refused download for %s (permission or unsupported type): %w", file.GetPath(), err)
}

Prevention

Check file permissions and downloadable file type before requesting links
For native docs route to the export flow rather than Link()
Patch the guard to include the probe status code so triage needs no reproduction

When it happens

Trigger: GET open.feishu.cn/open-apis/drive/v1/files/{token}/download returns non-206 — 403 (no permission on the file), 400 (file type not downloadable, e.g. native docs), 401 twice (both tokens rejected), or a redirect/login HTML page from a non-API gateway.

Common situations: User lacks download permission on the shared file; trying to 'download' a Feishu doc/sheet/bitable native file (needs export flow instead); expired download scope on the app token.

Related errors

AI-assisted analysis of AlistGo/alist@843d9dc814 (2026-08-15). Data as JSON: /api/errors/7792f7b8e7bfe6c3. Report an issue: GitHub.