{"record":{"id":"0a8983f629b5fb02","repo":"hashicorp/packer","slug":"error-uploading-envvarfile-s","errorCode":null,"errorMessage":"Error uploading envVarFile: %s","messagePattern":"Error uploading envVarFile: (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"provisioner/shell/provisioner.go","lineNumber":274,"sourceCode":"\t\t}\n\n\t\tp.config.envVarFile = tf.Name()\n\n\t\t// upload the var file\n\t\tvar cmd *packersdk.RemoteCmd\n\t\terr = retry.Config{StartTimeout: p.config.StartRetryTimeout}.Run(ctx, func(ctx context.Context) error {\n\t\t\tif _, err := tf.Seek(0, 0); err != nil {\n\t\t\t\treturn err\n\t\t\t}\n\n\t\t\tvar r io.Reader = tf\n\t\t\tif !p.config.Binary {\n\t\t\t\tr = &UnixReader{Reader: r}\n\t\t\t}\n\t\t\tremoteVFName := fmt.Sprintf(\"%s/%s\", p.config.RemoteFolder,\n\t\t\t\tfmt.Sprintf(\"varfile_%d.sh\", rand.Intn(9999)))\n\t\t\tif err := comm.Upload(remoteVFName, r, nil); err != nil {\n\t\t\t\treturn fmt.Errorf(\"Error uploading envVarFile: %s\", err)\n\t\t\t}\n\t\t\ttf.Close()\n\n\t\t\tcmd = &packersdk.RemoteCmd{\n\t\t\t\tCommand: fmt.Sprintf(\"chmod 0600 %s\", remoteVFName),\n\t\t\t}\n\t\t\tif err := comm.Start(ctx, cmd); err != nil {\n\t\t\t\treturn fmt.Errorf(\"Error chmodding script file to 0600 in remote machine: %s\", err)\n\t\t\t}\n\t\t\tcmd.Wait()\n\t\t\tp.config.envVarFile = remoteVFName\n\t\t\treturn nil\n\t\t})\n\t\tif err != nil {\n\t\t\treturn err\n\t\t}\n\t}\n","sourceCodeStart":256,"sourceCodeEnd":292,"githubUrl":"https://github.com/hashicorp/packer/blob/eb36e3c3e48a036f3e8cc94087636ee72e1303c9/provisioner/shell/provisioner.go#L256-L292","documentation":"After preparing the env-var temp file, Packer uploads it to the remote machine via the communicator's Upload inside a retry loop (provisioner/shell/provisioner.go:274). This error wraps a failed Upload of the var file to RemoteFolder. It means the communicator connection could not transfer the file — connection loss, authentication failure, or a bad remote path.","triggerScenarios":"comm.Upload(remoteVFName, ...) fails while retrying during Provision: SSH/WinRM connection dropped mid-provision, remote_folder is unwritable or missing, communicator credentials are wrong, or the remote machine was rebooted by a prior provisioner.","commonSituations":"A prior provisioner restarted the VM and the connection is still down; invalid ssh_private_key_file or wrong username; remote_folder pointing to a path that does not exist or lacks write permission; transient network flakiness on cloud instances.","solutions":["Verify communicator credentials and connectivity (ssh -i key user@host works manually).","Confirm remote_folder exists and is writable by the SSH user.","Increase start_retry_timeout so the retry loop survives slow reconnection after a reboot.","Add a pause_after or ensure restart provisioners wait for connectivity before the shell provisioner runs.","Run with PACKER_LOG=1 to inspect the underlying communicator error."],"exampleFix":"// before\nprovisioner \"shell\" {\n  use_env_var_file = true\n}\n// after — tolerate slow reconnects\nprovisioner \"shell\" {\n  use_env_var_file    = true\n  start_retry_timeout = \"15m\"\n}","handlingStrategy":"retry","validationCode":"// pre-flight connectivity check before packer build\nnc -z -w5 \"$SSH_HOST\" 22 && echo ok || { echo \"cannot reach $SSH_HOST:22\"; exit 1; }","typeGuard":null,"tryCatchPattern":"// the provisioner already retries within start_retry_timeout; surface the final error\nif err := p.Provision(ctx, ui, comm, data); err != nil {\n    var retriable = strings.Contains(err.Error(), \"Error uploading envVarFile\")\n    if retriable {\n        ui.Say(\"transient upload failure, re-running provisioner\")\n        // re-invoke or fail the build with context\n    }\n    return err\n}","preventionTips":["Set a generous start_retry_timeout when prior provisioners restart the machine.","Verify remote_folder exists and is writable by the communicator user.","Validate SSH credentials with a manual ssh login before running packer.","Avoid restarting the VM right before the shell provisioner without a wait."],"tags":["communicator","upload","ssh","network"],"backgroundTag":"communicator-upload-failed","analyzedSha":"eb36e3c3e48a036f3e8cc94087636ee72e1303c9","analyzedAt":"2026-09-05T13:20:43.127Z","contentChangedAt":"2026-09-05T13:20:43.127Z","schemaVersion":2},"datasetVersion":"2026-09-12T17:17:11.597Z"}