This happens because the container is running as a non-root user and doesn’t have permission to write to the directory it’s trying to use.

Many modern images intentionally drop root privileges for security reasons. That’s good practice, but it means directories owned by root are no longer writable unless you explicitly change ownership or permissions. This often shows up when mounting volumes or writing logs at runtime.

It’s especially confusing because everything may work fine locally if you were previously running the container as root.

Takeaway: Non-root containers are safer, but you must explicitly manage file ownership.