argoproj/argo-workflows · error

plugin %s save stream failed: %s

Error message

plugin %s save stream failed: %s

What it means

The SaveStream RPC completed at the transport level and returned a SaveResponse, but the plugin set Success=false with an application-level Error string. The driver surfaces the plugin's own message after 'save stream failed: '. This is plugin business-logic failure after receiving the full stream — not a network or protocol issue.

Source

Thrown at workflow/artifacts/plugin/plugin.go:297

			copy(chunk, buf[:n])
			if sendErr := sendFrame(&artifact.SaveStreamArtifactRequest{Chunk: chunk}, "mid-transfer"); sendErr != nil {
				return sendErr
			}
		}
		if errors.Is(readErr, io.EOF) {
			break
		}
		if readErr != nil {
			return fmt.Errorf("plugin %s save stream failed to read artifact content: %w", d.pluginName, readErr)
		}
	}

	resp, err := stream.CloseAndRecv()
	if err != nil {
		return fmt.Errorf("plugin %s save stream failed: %w", d.pluginName, err)
	}
	if !resp.Success {
		return fmt.Errorf("plugin %s save stream failed: %s", d.pluginName, resp.Error)
	}
	return nil
}

// supportsSaveStream reports whether the plugin advertises streaming support.
// A plugin that predates GetCapabilities returns codes.Unimplemented, which maps to
// (false, nil) so SaveStream falls back to the buffered Save. Any other error is
// returned rather than silently downgrading to buffering a potentially large artifact
// to disk before the real failure would resurface via Save.
func (d *Driver) supportsSaveStream(ctx context.Context) (bool, error) {
	resp, err := d.client.GetCapabilities(ctx, &artifact.GetCapabilitiesRequest{})
	if err != nil {
		if status.Code(err) == codes.Unimplemented {
			return false, nil
		}
		return false, fmt.Errorf("plugin %s get capabilities failed: %w", d.pluginName, err)
	}
	return resp.GetSupportsSaveStream(), nil

View on GitHub (pinned to 35bff19146)

Solutions

  1. Read the message after 'plugin <name> save stream failed: ' — it is the plugin's specific rejection reason
  2. Fix the artifact spec fields the plugin complained about (key, path, flags, metadata)
  3. Check destination storage permissions/quotas from the plugin pod if the error points at the backend
  4. Check plugin logs for the fuller error context behind the reported string
Defensive patterns

Strategy: validation

Validate before calling

// Validate artifact metadata the plugin will receive before streaming:
if outputArtifact.ArtifactLocation == nil || outputArtifact.ArtifactLocation.Key == nil {
    return fmt.Errorf("output artifact missing location/key for plugin save")
}

Type guard

func pluginRejectedSave(err error) (string, bool) {
    s := err.Error()
    if strings.Contains(s, "save stream failed: ") {
        i := strings.LastIndex(s, "save stream failed: ")
        return s[i+len("save stream failed: "):], true
    }
    return "", false
}

Try / catch

if err := driver.SaveStream(ctx, reader, artifact); err != nil {
    if reason, ok := pluginRejectedSave(err); ok {
        // deterministic plugin rejection: fix artifact config/permissions, do not blind-retry
        return fmt.Errorf("plugin rejected artifact (%s): %w", reason, err)
    }
    return err
}

Prevention

When it happens

Trigger: Calling Driver.SaveStream where stream.CloseAndRecv returns a response with resp.Success == false; the plugin received all chunks but rejected or failed the save, reporting why in resp.Error.

Common situations: Plugin rejected the artifact metadata (invalid key/path/flags), backend rejected the finalized object (permissions, quota, encryption policy), plugin-side validation of total size or checksum failed.

Related errors

AI-assisted analysis of argoproj/argo-workflows@35bff19146 (2026-09-03). Data as JSON: /api/errors/dd640ff5b1a1cc93. Report an issue: GitHub.