hashicorp/vagrant · error · Vagrant::Errors::UploaderError

An error occurred while uploading the file. The error messag

Error message

An error occurred while uploading the file. The error
message, if any, is reproduced below. Please fix this error and try
again.

exit code: %{exit_code}
%{message}

What it means

Raised by Vagrant::Util::Uploader after the underlying curl process it shells out to (Subprocess.execute("curl", ...)) exits with a non-zero status. The uploader is used for file uploads such as publishing boxes to Vagrant Cloud, and before raising it parses stderr for curl's '(code) message' pattern, falling back to raw stderr text when no match is found. The rendered message embeds both the curl exit code and that parsed text, so the actionable detail comes from curl itself.

Source

Thrown at lib/vagrant/util/uploader.rb:94

        result = Busy.busy(int_callback) do
          Subprocess.execute("curl", *options, &data_proc)
        end

        # If the upload was interrupted, then raise a specific error
        raise Errors::UploaderInterrupted if interrupted

        # If it didn't exit successfully, we need to parse the data and
        # show an error message.
        if result.exit_code != 0
          @logger.warn("Uploader exit code: #{result.exit_code}")
          check = result.stderr.match(/\n*curl:\s+\((?<code>\d+)\)\s*(?<error>.*)$/)
          if !check
            err_msg = result.stderr
          else
            err_msg = check[:error]
          end

          raise Errors::UploaderError,
            exit_code: result.exit_code,
            message: err_msg
        end

        if @ui
          @ui.clear_line
          # Windows doesn't clear properly for some reason, so we just
          # output one more newline.
          @ui.detail("") if Platform.windows?
        end
        result
      end
    end
  end
end

View on GitHub (pinned to 35f3160f4a)

Solutions

Read the embedded curl message and exit code - `curl: (22) ... 401` points at auth, `(7) Failed to connect` at network, `(60) SSL certificate problem` at TLS interception
If it is an auth failure, refresh credentials with `vagrant cloud auth login` and retry the upload
Reproduce outside Vagrant with `curl -v -T <file> <url>` to see the raw HTTP/TLS exchange
Check and (if wrong) unset or fix proxy environment variables (http_proxy, https_proxy, no_proxy)
Retry once transient causes (timeout, connection reset) are ruled out or resolved

Example fix

# before
vagrant cloud publish myuser/mybox 1.0.0 virtualbox package.box
# -> error, curl message shows: curl: (22) The requested URL returned error: 401

# after
vagrant cloud auth login   # or: export VAGRANT_CLOUD_TOKEN=...
vagrant cloud publish myuser/mybox 1.0.0 virtualbox package.box

Defensive patterns

Strategy: try-catch

Validate before calling

# bash: verify cloud session + endpoint before a long publish
vagrant cloud auth whoami >/dev/null 2>&1 || vagrant cloud auth login
curl -fsSI -o /dev/null https://app.vagrantup.com/ || { echo 'upload endpoint unreachable'; exit 1; }

Try / catch

begin
  Vagrant::Util::Uploader.new(ui, url, uploader_options).upload!
rescue Vagrant::Errors::UploaderError => e
  code = e.extra_data[:exit_code].to_i
  retry if [28, 56].include?(code) # transient curl timeout / recv reset: retry once
  raise                          # auth (22/401), TLS (60), connect (7): surface to caller
end

Prevention

Run `vagrant cloud auth login` or set VAGRANT_CLOUD_TOKEN before scripted publishes
Smoke-test connectivity to the upload host with `curl -I` in CI before the long upload
Verify http_proxy/https_proxy/no_proxy in CI jobs point at a live proxy
Keep curl on PATH and reasonably recent - the uploader shells out to it directly

When it happens

Trigger: Any code path that uses the Uploader utility - chiefly `vagrant cloud publish` / box upload flows - where curl fails: HTTP 401/403 from an expired or missing cloud token, curl exit 7 (connection failed), exit 6 (DNS), exit 28 (timeout), exit 55/56 (send/recv errors), or exit 60 (TLS certificate verification failure).

Common situations: Expired or missing Vagrant Cloud token; corporate proxy or TLS-intercepting firewall breaking curl; unreachable upload endpoint; redirect loops; http_proxy/https_proxy environment variables pointing at a dead proxy in CI runners.

Related errors

AI-assisted analysis of hashicorp/vagrant@35f3160f4a (2026-08-21). Data as JSON: /api/errors/2165aa4ed206d385. Report an issue: GitHub.