{"record":{"id":"b018ec0201ded4c3","repo":"caddyserver/caddy","slug":"config-is-not-valid-json-w-at-offset-d-did-yo","errorCode":null,"errorMessage":"config is not valid JSON: %w, at offset %d; did you mean to use a config adapter (the --adapter flag)?","messagePattern":"config is not valid JSON: %w, at offset (.+?); did you mean to use a config adapter \\(the --adapter flag\\)\\?","errorType":"console","errorClass":null,"httpStatus":null,"severity":"error","filePath":"cmd/main.go","lineNumber":235,"sourceCode":"\t\t}\n\t\tlogger.Info(\"adapted config to JSON\", zap.String(\"adapter\", adapterName))\n\t\tfor _, warn := range warnings {\n\t\t\tmsg := warn.Message\n\t\t\tif warn.Directive != \"\" {\n\t\t\t\tmsg = fmt.Sprintf(\"%s: %s\", warn.Directive, warn.Message)\n\t\t\t}\n\t\t\tlogger.Warn(msg,\n\t\t\t\tzap.String(\"adapter\", adapterName),\n\t\t\t\tzap.String(\"file\", warn.File),\n\t\t\t\tzap.Int(\"line\", warn.Line))\n\t\t}\n\t\tconfig = adaptedConfig\n\t} else if len(config) != 0 {\n\t\t// validate that the config is at least valid JSON\n\t\terr = json.Unmarshal(config, new(any))\n\t\tif err != nil {\n\t\t\tif jsonErr, ok := err.(*json.SyntaxError); ok {\n\t\t\t\treturn nil, \"\", \"\", fmt.Errorf(\"config is not valid JSON: %w, at offset %d; did you mean to use a config adapter (the --adapter flag)?\", err, jsonErr.Offset)\n\t\t\t}\n\t\t\treturn nil, \"\", \"\", fmt.Errorf(\"config is not valid JSON: %w; did you mean to use a config adapter (the --adapter flag)?\", err)\n\t\t}\n\t}\n\n\treturn config, configFile, adapterName, nil\n}\n\n// watchConfigFile watches the config file at filename for changes\n// and reloads the config if the file was updated. This function\n// blocks indefinitely; it only quits if the poller has errors for\n// long enough time. The filename passed in must be the actual\n// config file used, not one to be discovered.\n// Each second the config files is loaded and parsed into an object\n// and is compared to the last config object that was loaded\nfunc watchConfigFile(filename, adapterName string) {\n\tdefer func() {\n\t\tif err := recover(); err != nil {","sourceCodeStart":217,"sourceCodeEnd":253,"githubUrl":"https://github.com/caddyserver/caddy/blob/50e54ee279aa1e504fe218ca49ab6ae16c100410/cmd/main.go#L217-L253","documentation":"No adapter applied, so Caddy validated the raw config as JSON and hit a json.SyntaxError — structural JSON breakage (trailing comma, unquoted key, stray character). The byte offset of the failure is included, and the hint suggests --adapter for non-JSON inputs. This is the offset-carrying variant of the two JSON validation messages.","triggerScenarios":"Passing a Caddyfile (or YAML etc.) as --config without --adapter; hand-edited JSON config with a syntax slip; the offset in the message maps directly to the offending byte.","commonSituations":"Forgetting that JSON, not Caddyfile, is the native format; tools emitting near-JSON (comments, trailing commas) that strict encoding/json rejects.","solutions":["If the file is a Caddyfile, add --adapter caddyfile (or name the file 'Caddyfile' for auto-detection)","If it is JSON, jump to the reported offset and fix the syntax error","Lint first: jq . config.json — jq pinpoints the same offset"],"exampleFix":"# before\ncaddy run --config Caddyfile.prod          # it is Caddyfile syntax, parsed as JSON\n\n# after\ncaddy run --config Caddyfile.prod --adapter caddyfile","handlingStrategy":"validation","validationCode":"// Detect non-JSON input up front and require an adapter:\nif !json.Valid(rawConfig) { if adapterName == \"\" { return errors.New(\"config is not JSON; pass --adapter (e.g. caddyfile)\") } }","typeGuard":"func looksLikeJSON(b []byte) bool { t := bytes.TrimSpace(b); return len(t) > 0 && (t[0] == '{' || t[0] == '[') }","tryCatchPattern":null,"preventionTips":["Name Caddyfile-syntax files 'Caddyfile*' for auto-detection","Always pass --adapter for non-JSON config formats","Use the reported byte offset to jump straight to the syntax error"],"tags":["cli","configuration","json","syntax-error"],"backgroundTag":null,"analyzedSha":"50e54ee279aa1e504fe218ca49ab6ae16c100410","analyzedAt":"2026-08-15T09:20:21.641Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}