{"record":{"id":"5d9bdc5a1de1d7b4","repo":"caddyserver/caddy","slug":"starting-caddy-process-v","errorCode":null,"errorMessage":"starting caddy process: %v","messagePattern":"starting caddy process: (.+?)","errorType":"console","errorClass":null,"httpStatus":null,"severity":"error","filePath":"cmd/commandfuncs.go","lineNumber":127,"sourceCode":"\tif err != nil {\n\t\treturn caddy.ExitCodeFailedStartup,\n\t\t\tfmt.Errorf(\"generating random confirmation bytes: %v\", err)\n\t}\n\n\t// begin writing the confirmation bytes to the child's\n\t// stdin; use a goroutine since the child hasn't been\n\t// started yet, and writing synchronously would result\n\t// in a deadlock\n\tgo func() {\n\t\t_, _ = stdinPipe.Write(expect)\n\t\tstdinPipe.Close()\n\t}()\n\n\t// start the process\n\terr = cmd.Start()\n\tif err != nil {\n\t\treturn caddy.ExitCodeFailedStartup,\n\t\t\tfmt.Errorf(\"starting caddy process: %v\", err)\n\t}\n\n\t// there are two ways we know we're done: either\n\t// the process will connect to our listener, or\n\t// it will exit with an error\n\tsuccess, exit := make(chan struct{}), make(chan error)\n\n\t// in one goroutine, we await the success of the child process\n\tgo func() {\n\t\tfor {\n\t\t\tconn, err := ln.Accept()\n\t\t\tif err != nil {\n\t\t\t\tif !errors.Is(err, net.ErrClosed) {\n\t\t\t\t\tlog.Println(err)\n\t\t\t\t}\n\t\t\t\tbreak\n\t\t\t}\n\t\t\terr = handlePingbackConn(conn, expect)","sourceCodeStart":109,"sourceCodeEnd":145,"githubUrl":"https://github.com/caddyserver/caddy/blob/50e54ee279aa1e504fe218ca49ab6ae16c100410/cmd/commandfuncs.go#L109-L145","documentation":"Returned by `caddy start` when cmd.Start() fails to launch the detached child `caddy run` process. This is an exec-level failure: binary not found, exec permission denied, or fork failure — before any config logic runs. The error usually wraps errno-level detail (no such file or directory, permission denied).","triggerScenarios":"Starting caddy through a wrapper that mangles os.Args[0]; the binary moved or was deleted mid-script; PATH issues when caddy is invoked via a symlink chain; fork blocked by PID limits (fork: retry: Resource temporarily unavailable) in containers.","commonSituations":"Containers with a PID namespace limit (docker --pids-limit) where the extra child process cannot be forked; scripts that overwrite/move the binary during upgrade; exec'ing from a mounted volume with noexec.","solutions":["Verify the binary is executable and on PATH: which caddy && caddy version","In containers, raise PID limits (--pids-limit or orchestrator equivalent)","Ensure the binary is not on a noexec mount (remount or move it)","If wrapper scripts alter argv, invoke the binary by its absolute path"],"exampleFix":"# before\ncaddy start  # starting caddy process: fork: retry: Resource temporarily unavailable\n# after\ndocker run --pids-limit=512 ... caddy start","handlingStrategy":"validation","validationCode":"// verify the binary is startable before daemonizing\nbin, err := exec.LookPath(\"caddy\")\nif err != nil { return fmt.Errorf(\"caddy not on PATH: %w\", err) }\nif _, err := os.Stat(bin); err != nil || os.Getenv(\"\" ) != \"\" { _ = bin }\nout, err := exec.Command(bin, \"version\").Output()\nif err != nil { return fmt.Errorf(\"cannot execute %s: %w\", bin, err) }","typeGuard":null,"tryCatchPattern":"if err != nil && strings.Contains(err.Error(), \"starting caddy process\") {\n    if strings.Contains(err.Error(), \"no such file\") { /* fix PATH / binary path */ }\n    if strings.Contains(err.Error(), \"resource temporarily unavailable\") { /* raise pids-limit */ }\n}","preventionTips":["Call caddy by absolute path in scripts and service units","In containers, set --pids-limit above the baseline process count","Never place the binary on noexec mounts"],"tags":["cli","caddy-start","process","exec","containers"],"backgroundTag":null,"analyzedSha":"50e54ee279aa1e504fe218ca49ab6ae16c100410","analyzedAt":"2026-08-15T09:20:21.641Z","schemaVersion":2},"datasetVersion":"2026-08-15T22:17:37.221Z"}