The pack folder cannot be written to

Chip support is cached in a folder under your user account. That folder refused to be written to, so the download had nowhere to go.

PACK_CACHE_UNWRITABLE

Symptoms

  • The pack download fails immediately, before any progress is shown.
  • It fails the same way every time, with the network plainly working.

Likely causes

  • The cache folder is owned by another user — usually created by a run under sudo or by a different account.
  • The folder sits on a read-only volume, a network share or a synced folder that blocks writes.
  • Security software or a managed-device policy protects the application-data directory.

How to fix it

  1. Find the folder in the message on the error card

    The technical detail names the exact path. By default it is:

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

  2. Give your own account ownership of it

    On macOS and Linux, a folder created under sudo stays owned by root and the app can never write to it.

    sudo chown -R "$USER" ~/Library/Application\ Support/cmsis-pack-manager

  3. Or delete it and let it be recreated

    With the SDK closed, remove the folder. The next chip you pick recreates it under your own account, and nothing is permanently lost.

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