Prism Launcher Java & JVM Configuration
Match the exact Java runtime (Java 21, Java 17, or Java 8) to your Minecraft version, tune min/max RAM, and pass GC JVM arguments.
Fix "failed to create the java virtual machine" in Prism Launcher: Java runtime, memory slider, and instance log.
"prism launcher failed to create the java virtual machine" is a common support search. Read the instance log before reinstalling the pack.
Match Java to the Minecraft version (8 / 17 / 21). Do not give a 1.16 pack Java 21 unless the pack says so.
Installer: /download.

Prism can fetch a matching runtime. Point the instance at that install.
Free and open source. Sign in with the Microsoft account that owns Minecraft, then create your first instance.
