What causes "can't set severity rule option: no default severity defined" in golangci/golangci-lint?

Add a 'default' severity option in the severity config section, e.g. severity: default: error

can't set severity rule option: no default severity defined

Error message

can't set severity rule option: no default severity defined

What it means

The severity configuration section (used by the severity-rules linter) requires a 'default' severity whenever any severity 'rules' are defined. golangci-lint throws this during config validation because without a default severity, rules that do not match would leave diagnostics with no assigned severity. It is thrown by Severity.Validate() before linting begins.

Source

Thrown at pkg/config/severity.go:17

package config

import (
	"errors"
	"fmt"
)

const severityRuleMinConditionsCount = 1

type Severity struct {
	Default string         `mapstructure:"default"`
	Rules   []SeverityRule `mapstructure:"rules"`
}

func (s *Severity) Validate() error {
	if len(s.Rules) > 0 && s.Default == "" {
		return errors.New("can't set severity rule option: no default severity defined")
	}

	for i, rule := range s.Rules {
		if err := rule.Validate(); err != nil {
			return fmt.Errorf("error in severity rule #%d: %w", i, err)
		}
	}

	return nil
}

type SeverityRule struct {
	BaseRule `mapstructure:",squash"`
	Severity string `mapstructure:"severity"`
}

func (s *SeverityRule) Validate() error {
	if s.Severity == "" {

View on GitHub (pinned to ed7a235d2d)

Solutions

Add a 'default' severity option in the severity config section, e.g. severity: default: error
For the legacy setting, set default-severity in severity-rules configuration
If rules are unnecessary, remove the severity rules entries so validation passes
Run golangci-lint config verify to confirm the severity section is well-formed

Example fix

// before (.golangci.yml)
severity:
  rules:
    - text: "unused"
      severity: warning

// after
severity:
  default: error
  rules:
    - text: "unused"
      severity: warning

Defensive patterns

Strategy: validation

Validate before calling

if cfg.Severity != nil && len(cfg.Severity.Rules) > 0 && cfg.Severity.Default == "" {
    return fmt.Errorf("severity rules defined but 'default' severity is missing")
}

Prevention

Always pair severity rules with a default severity in the same config block
Run 'golangci-lint config verify' in CI before linting
When migrating from severity-rules, carry over default-severity

When it happens

Trigger: Config contains [severity.rules] entries (e.g. matching text or source patterns) but the [severity] (or severity-rules) section has no 'default' key set. Also triggered when rules exist via the deprecated 'severity-rules' setting without 'default-severity'.

Common situations: Users copy a severity-rules example from documentation or a blog post that only shows the rules, omitting default-severity; upgrading golangci-lint after the option moved into the severity section; YAML indentation mistakes that put rules under severity while default stays unset.

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 golangci/golangci-lint@ed7a235d2d (2026-09-02). Data as JSON: /api/errors/2292b4090d9a750c. Report an issue: GitHub.