Java HttpClient NullPointerException ("this.http" is null) on Startup

What it looks like in the log

java.lang.NullPointerException: Cannot invoke "sun.net.www.http.HttpClient.getOutputStream()" because "this.http" is null

How to fix it

1. Disable your operating system's global network proxy (for example, in KDE System Settings > Network > Proxy or GNOME Network settings) before opening the launcher.
2. If you need a proxy to download files or log in, configure the proxy directly inside your launcher's own network settings (such as HMCL Settings > Download > Proxy) using an explicit HTTP or SOCKS5 host and port instead of choosing 'Follow System Proxy'.
3. If launching via a custom script or desktop shortcut on Linux, add the JVM flag -Djava.net.useSystemProxies=false to prevent Java from reading broken desktop proxy environment variables.
4. Update your launcher to the latest official release rather than an outdated snapshot or unofficial package build, as newer builds handle proxy and network fallbacks more cleanly.

Check your own log