hashicorp/packer · error

failed to open temp file: %w

Error message

failed to open temp file: %w

What it means

Despite the message, this error is not about creating the temp file: it fires when opening an entry inside the already-downloaded plugin zip archive fails. In InstallLatest, after the plugin zip is written to a temp file and opened with zip.OpenReader, the entry matching the expected plugin binary filename is located and f.Open() is called to get a reader for that entry; if that per-entry open fails (corrupt or truncated download, unsupported compression method, CRC/layout problems within the archive), the wrapped error is appended to the multierror list and installation of the plugin is aborted.

Source

Thrown at packer/plugin-getter/plugins.go:861

					if err := checksum.Checksummer.Checksum(checksum.Expected, tmpFile); err != nil {
						err := fmt.Errorf("%w. Is the checksum file correct ? Is the binary file correct ?", err)
						errs = multierror.Append(errs, err)
						continue
					}
					zr, err := zip.OpenReader(tmpFile.Name())
					if err != nil {
						errs = multierror.Append(errs, fmt.Errorf("zip : %v", err))
						return nil, errs
					}

					var copyFrom io.ReadCloser
					for _, f := range zr.File {
						if f.Name != expectedBinaryFilename {
							continue
						}
						copyFrom, err = f.Open()
						if err != nil {
							errs = multierror.Append(errs, fmt.Errorf("failed to open temp file: %w", err))
							return nil, errs
						}
						break
					}
					if copyFrom == nil {
						err := fmt.Errorf("could not find a %q file in zipfile", expectedBinaryFilename)
						errs = multierror.Append(errs, err)
						return nil, errs
					}

					var outputFileData bytes.Buffer
					if _, err := io.Copy(&outputFileData, copyFrom); err != nil {
						err := fmt.Errorf("extract file: %w", err)
						errs = multierror.Append(errs, err)
						return nil, errs
					}
					tmpBinFileName := filepath.Join(os.TempDir(), expectedBinaryFilename)
					tmpOutputFile, err := os.OpenFile(tmpBinFileName, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0755)

View on GitHub (pinned to eb36e3c3e4)

Solutions

1. Check the full download/verification log above this error: a checksum mismatch that was skipped or a truncated network transfer usually precedes a corrupt zip entry
2. Delete the cached plugin download and retry `packer init` so the plugin zip is fetched again
3. Verify the plugin's released zip artifact on the origin server is valid (open it manually with `unzip -t`), and report it to the plugin maintainer if it is broken
4. If running behind a proxy or cached mirror, bypass it and re-download, since proxies sometimes corrupt binary zip content

When it happens

Trigger: Thrown at packer/plugin-getter/plugins.go:861 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of hashicorp/packer@eb36e3c3e4 (2026-09-05). Data as JSON: /api/errors/81b44975a43cf90a. Report an issue: GitHub.