The issue is almost certainly caused by an empty or whitespace-only environment variable name defined in the Railway Service or Shared Environment settings.When Railpack constructs the build plan, it mounts all environment variables as BuildKit secrets. If a variable key contains leading/trailing whitespace (e.g., " LUAVEX_ACCOUNT_STATE_DIR") or an empty key/blank line exists in the environment settings, BuildKit receives an empty secret ID (id=""), causing failed to solve: secret ID missing for "" environment variable. Suggested Response to the UserHi @iqubex,This error occurs when BuildKit receives a secret mount request with a blank or whitespace-padded key name. When Railpack builds the container image, it maps your service's environment variables as build secrets. If an environment variable name starts or ends with a space, or if an empty line/key exists, Railpack attempts to pass an empty key to BuildKit. How to Resolve1.Check for Leading or Trailing Whitespace:Go to your service's Variables tab in Railway (or Raw Editor mode) and check every key name—especially recent additions like LUAVEX_ACCOUNT_STATE_DIR. Ensure there are no accidental leading spaces (e.g., " LUAVEX_ACCOUNT_STATE_DIR" instead of LUAVEX_ACCOUNT_STATE_DIR) or trailing spaces.2.Inspect Raw / Bulk Editor:Switch to the Raw Editor view in the Variables tab. Look for:Any empty key-value lines (e.g., a blank line between entries).Lines starting with =value (missing key name).3.Verify Shared & Environment-Level Variables:If your service inherits variables from a Shared Variable Group or environment-level config, check those for empty or whitespace-padded key names as well.4.Save and Redeploy:Once any padded or empty variable keys are removed, trigger a new deployment.After fixing the key name, the step will succeed: check your Build Logs during the install apt packages phase to confirm BuildKit solves the layer successfully.