What causes "configuration file not found" in golangci/golangci-lint?

Create a `.custom-gcl.yml` file in the directory where you run the command, with `version` and `plugins` fields

configuration file not found

Error message

configuration file not found

What it means

`findConfigurationFile` (pkg/commands/internal/configuration.go:135) scans the current directory for a file named `.custom-gcl.yml`, `.custom-gcl.yaml`, or `.custom-gcl.json` (exact base name `.custom-gcl` plus a supported extension, checked by `isConf`). If none exists it returns this error, which `LoadConfiguration` wraps as `file not found: configuration file not found`. Unlike golangci-lint itself, the custom builder does not search parent directories or other config names.

Source

Thrown at pkg/commands/internal/configuration.go:135

func findConfigurationFile() (string, error) {
	entries, err := os.ReadDir(".")
	if err != nil {
		return "", fmt.Errorf("read directory: %w", err)
	}

	for _, entry := range entries {
		ext := filepath.Ext(entry.Name())

		switch strings.ToLower(strings.TrimPrefix(ext, ".")) {
		case "yml", "yaml", "json":
			if isConf(ext, entry.Name()) {
				return entry.Name(), nil
			}
		}
	}

	return "", errors.New("configuration file not found")
}

func isConf(ext, name string) bool {
	return base+ext == name
}

View on GitHub (pinned to ed7a235d2d)

Solutions

Create a `.custom-gcl.yml` file in the directory where you run the command, with `version` and `plugins` fields
cd to the directory that actually contains the `.custom-gcl.*` file before running the build
Check the exact file name — it must start with a dot and be exactly `.custom-gcl` + .yml/.yaml/.json (no other suffixes)

Example fix

# wrong: custom-gcl.yml (no leading dot) — not found
# after
mv custom-gcl.yml .custom-gcl.yml

Defensive patterns

Strategy: validation

Validate before calling

const base = ".custom-gcl"
found := false
for _, ext := range []string{".yml", ".yaml", ".json"} {
	if _, err := os.Stat(base + ext); err == nil {
		found = true
		break
	}
}
if !found {
	log.Fatal("no .custom-gcl.{yml,yaml,json} in current directory")
}

Prevention

Run custom-gcl commands from the directory containing the .custom-gcl.* file
Use the exact name `.custom-gcl.yml` (leading dot, no extra suffixes)
Remember there is no parent-directory search, unlike .golangci.yml

When it happens

Trigger: Running the custom golangci-lint build command from a directory that contains no `.custom-gcl.{yml,yaml,json}` file — e.g. running it in a subdirectory or repo root when the config lives elsewhere.

Common situations: Running the command from the wrong working directory; naming the file `.custom-gcl.yaml.dist`, `custom-gcl.yml` (missing leading dot), or `.custom.gcl.yml` — `isConf` requires the exact name; the config only exists in a parent directory since there is no upward search.

Understand the failure class

Background: "Config file not found": what it means and how to fix it in docker-sync, Maven, Vagrant, Turborepo and other tools — this error's family across 60 libraries.

Related errors

AI-assisted analysis of golangci/golangci-lint@ed7a235d2d (2026-09-02). Data as JSON: /api/errors/f0c4c583ac01eb7f. Report an issue: GitHub.