ClassNotFoundException: net.minecraft.launchwrapper.Launch

What the log looks like

java\.lang\.ClassNotFoundException: net\.minecraft\.launchwrapper\.Launch
net/minecraft/launchwrapper/[\d.]+/launchwrapper-[\d.]+\.jar \(missing\)

How to fix it

1. Connect to the internet and launch the game in Online Mode at least once so your launcher can download missing Forge and launchwrapper files.
2. In MultiMC or Prism Launcher, right-click the instance, click Edit -> Version, remove the broken Forge/OptiFine patches, and reinstall Forge using the built-in Install Forge button.
3. If using both Forge and OptiFine, remove any OptiFine version patches in your launcher settings and place the downloaded OptiFine JAR directly into your instance's mods folder instead.
4. Do not share a single .minecraft directory between multiple third-party launchers (such as HMCL and PCL); create a clean, separate game directory or instance in one launcher and reinstall Forge.

Check your own log