The pack server did not answer

Support for a chip is downloaded from the CMSIS-Pack servers the first time you pick it. This machine is online, but that download could not reach them, so nothing was installed and nothing was changed.

PACK_NETWORK_UNREACHABLE

Symptoms

  • Choosing a chip fails during "Downloading pack index..." or "Downloading pack...".
  • The chip search lists only a handful of parts, with a note that the list is incomplete.
  • Everything else in MCUHex works — the board connects, values read.

Likely causes

  • No route to the CMSIS-Pack servers: the index comes from keil.com, and the pack files themselves come from the silicon vendor’s own server.
  • A company proxy or VPN allows browsing but blocks the direct HTTPS connection this download makes.
  • A firewall permits the browser and not the MCUHex desktop app, which is the process doing the download.
  • The vendor’s pack server is temporarily down — the index resolves, the pack does not arrive.

How to fix it

  1. Confirm the pack servers are reachable from this machine

    The index host is the first thing MCUHex needs. If this fails while your browser works, something between you and it is filtering.

    curl -I https://www.keil.com/pack/index.pidx

  2. Let the desktop app through the proxy

    On a corporate network, allow the MCUHex app itself — not just the browser — to reach keil.com and your vendor’s domain (st.com, nxp.com, microchip.com and the like).

  3. Use a chip that needs no download

    Targets pyOCD ships are marked as needing no pack in the chip list. They apply offline and are enough to connect, monitor and flash a supported part.

  4. Install the pack by hand

    Download the .pack file from the vendor on any machine that can reach them, then place it in the cache folder and restart the SDK.

    macOS    ~/Library/Application Support/cmsis-pack-manager
Linux    ~/.local/share/cmsis-pack-manager
Windows  %LOCALAPPDATA%\cmsis-pack-manager

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