lunachrome

Chrome will not install an extension it did not sign

This is not a warning you can click through. Chromium requires every extension to carry a cryptographic proof from Google, and no one outside Google can produce one. A downloaded package dragged onto the extensions page fails with CRX_REQUIRED_PROOF_MISSING, on Windows since Chrome 33 and on macOS since Chrome 44.

So there is no install button here. Offering one would be a lie. Two paths genuinely work, and which one you want depends on whether you are setting up your own machine or a fleet of them.

For your own machine

Load the extension unpacked. Chrome keeps it enabled as long as Developer mode stays on. This is the supported developer path, not a workaround.

Download luna-chrome.zip
  1. 1

    Download the package

    luna-chrome.zip, then unzip it somewhere permanent — Chrome loads it from that folder every launch, so a Downloads folder you clear out will break it.

  2. 2

    Open chrome://extensions

    Paste the address; Chrome blocks links to it from web pages.

  3. 3

    Turn on Developer mode

    Top right. It has to stay on, or Chrome disables the extension.

  4. 4

    Choose Load unpacked

    Select the unzipped folder — the one containing manifest.json.

For a managed fleet

Enterprise policy is the one supported way to install a self-hosted extension permanently. It needs administrator rights, and on Windows and macOS the machine must also be domain-joined or MDM-enrolled — Chrome refuses policy-installed off-store extensions otherwise.

Policy-installed packages are verified without Google’s proof, so a self-signed build is accepted on this path. Note that any non-default policy makes Chrome show “Managed by your organization” in its menu.

# Linux — /etc/opt/chrome/policies/managed/luna.json
{
  "ExtensionInstallForcelist": [
    "<extension-id>;https://luna.mosphox.com/chrome/update.xml"
  ]
}

# Windows — HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome
#   ExtensionInstallForcelist\1 (REG_SZ)
#   = "<extension-id>;https://luna.mosphox.com/chrome/update.xml"

# macOS — com.google.Chrome, delivered as an MDM configuration profile
#   ExtensionInstallForcelist = ["<extension-id>;https://…/update.xml"]