What causes "unknown parameter %s" in crowdsecurity/crowdsec?

Remove the unknown parameter from the DSN.

unknown parameter %s

Error message

unknown parameter %s

What it means

ConfigureByDSN iterates the DSN query parameters and rejects any key it does not recognize with this error. Only the S3 source's supported parameters (e.g. log_level, max_buffer_size, and other documented keys) are allowed.

Source

Thrown at pkg/acquisition/modules/s3/config.go:247

				if err != nil {
					return fmt.Errorf("unknown level %s: %w", value[0], err)
				}

				s.logger.Logger.SetLevel(lvl)
			case "max_buffer_size":
				if len(value) != 1 {
					return errors.New("expected zero or one value for 'max_buffer_size'")
				}

				maxBufferSize, err := strconv.Atoi(value[0])
				if err != nil {
					return fmt.Errorf("invalid value for 'max_buffer_size': %w", err)
				}

				s.logger.Debugf("Setting max buffer size to %d", maxBufferSize)
				s.Config.MaxBufferSize = maxBufferSize
			default:
				return fmt.Errorf("unknown parameter %s", key)
			}
		}
	}

	s.Config.Labels = labels
	s.Config.Mode = configuration.CAT_MODE
	s.Config.UniqueId = uuid

	pathParts := strings.Split(args[0], "/")
	s.logger.Debugf("pathParts: %v", pathParts)

	// FIXME: handle s3://bucket/
	if len(pathParts) == 1 {
		s.Config.BucketName = pathParts[0]
		s.Config.Prefix = ""
	} else if len(pathParts) > 1 {
		s.Config.BucketName = pathParts[0]
		if args[0][len(args[0])-1] == '/' {

View on GitHub (pinned to 909b515798)

Solutions

Remove the unknown parameter from the DSN.
Check the S3 acquisition documentation for the exact supported parameter names.
Check for typos or renamed options (e.g. max_buffer_size vs maxBufferSize).

Example fix

// before
crowdsec-s3://mybucket?bufffer_size=1024
// after
crowdsec-s3://mybucket?max_buffer_size=1024

Defensive patterns

Strategy: validation

Validate before calling

allowed := map[string]bool{"log_level":true, "max_buffer_size":true /* + other supported keys */}
for key := range params {
    if !allowed[key] { return fmt.Errorf("unsupported S3 DSN parameter %q", key) }
}

Prevention

Copy DSN parameters only from the same source type's documentation.
Validate DSNs in CI with a config parse step.
Re-check parameter names after upgrading crowdsec.

When it happens

Trigger: A DSN such as crowdsec-s3://bucket?region=us-east-1&foo=bar where a key is not in the source's switch statement — either a genuinely unsupported option, a renamed option, or a typo.

Common situations: Copy-pasting DSN options from another data source (e.g. kafka or cloudwatch options); guessing parameter names; options removed or renamed in a newer crowdsec version.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

AI-assisted analysis of crowdsecurity/crowdsec@909b515798 (2026-09-06). Data as JSON: /api/errors/754bab3a0b445d81. Report an issue: GitHub.