{"record":{"id":"1902a46c2f9e4c8e","repo":"caddyserver/caddy","slug":"download-succeeded-but-unable-to-execute-caddy-v","errorCode":null,"errorMessage":"download succeeded, but unable to execute 'caddy version': %v","messagePattern":"download succeeded, but unable to execute 'caddy version': (.+?)","errorType":"console","errorClass":null,"httpStatus":null,"severity":"error","filePath":"cmd/packagesfuncs.go","lineNumber":198,"sourceCode":"\t\t}\n\t}()\n\n\t// download the file; do this in a closure to close reliably before we execute it\n\terr = writeCaddyBinary(thisExecPath, &resp.Body, thisExecStat)\n\tif err != nil {\n\t\treturn caddy.ExitCodeFailedStartup, err\n\t}\n\n\tl.Info(\"download successful; displaying new binary details\", zap.String(\"location\", thisExecPath))\n\n\t// use the new binary to print out version and module info\n\tfmt.Print(\"\\nModule versions:\\n\\n\")\n\tif err = listModules(thisExecPath); err != nil {\n\t\treturn caddy.ExitCodeFailedStartup, fmt.Errorf(\"download succeeded, but unable to execute 'caddy list-modules': %v\", err)\n\t}\n\tfmt.Println(\"\\nVersion:\")\n\tif err = showVersion(thisExecPath); err != nil {\n\t\treturn caddy.ExitCodeFailedStartup, fmt.Errorf(\"download succeeded, but unable to execute 'caddy version': %v\", err)\n\t}\n\tfmt.Println()\n\n\t// clean up the backup file\n\tif !fl.Bool(\"keep-backup\") {\n\t\tif err = removeCaddyBinary(backupExecPath); err != nil {\n\t\t\treturn caddy.ExitCodeFailedStartup, fmt.Errorf(\"download succeeded, but unable to clean up backup binary: %v\", err)\n\t\t}\n\t} else {\n\t\tl.Info(\"skipped cleaning up the backup file\", zap.String(\"backup_path\", backupExecPath))\n\t}\n\n\tl.Info(\"upgrade successful; please restart any running Caddy instances\", zap.String(\"executable\", thisExecPath))\n\n\treturn caddy.ExitCodeSuccess, nil\n}\n\nfunc getModules() (standard, nonstandard, unknown []moduleInfo, err error) {","sourceCodeStart":180,"sourceCodeEnd":216,"githubUrl":"https://github.com/caddyserver/caddy/blob/50e54ee279aa1e504fe218ca49ab6ae16c100410/cmd/packagesfuncs.go#L180-L216","documentation":"Same post-install verification step as the list-modules check, but for the '<newexec> version' subprocess. The new binary already replaced the old one and module listing succeeded, so a failure here is specifically about executing the binary a second time or it exiting non-zero. Because err is non-zero on return, the deferred handler restores the original binary from the .tmp backup.","triggerScenarios":"Intermittent exec failure (AV scanning the file between runs), the binary exiting non-zero for 'version' specifically, or resource exhaustion preventing process spawn (fork failure, PID limits in containers).","commonSituations":"Antivirus/EDR on Windows intercepting repeated executions of a freshly written file; a hardened container hitting process limits during upgrade; rarely, a genuinely broken build.","solutions":["Run 'caddy version' manually to confirm the installed binary works; if it does, the failure was environmental","Re-run the upgrade command","Disable/reconfigure antivirus real-time scanning for the caddy executable path","If in a container, raise the process/PID limit or upgrade outside the container"],"exampleFix":null,"handlingStrategy":"validation","validationCode":"caddy version   # run once manually; if this works, a failed in-upgrade check was environmental","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Re-run the upgrade when exec verification fails intermittently (AV scanning)","Verify disk and process resources in containers before upgrading"],"tags":["upgrade","exec","subprocess","cli"],"backgroundTag":null,"analyzedSha":"50e54ee279aa1e504fe218ca49ab6ae16c100410","analyzedAt":"2026-08-15T09:20:21.641Z","schemaVersion":2},"datasetVersion":"2026-08-15T17:31:12.345Z"}