game chrashes when i hit play in launcher

17:19:26
launcher
main
info
Preparing to launch minecraft client for 1.14.2
17:19:26
launcher
main
info
Checking installations.
17:19:26
launcher
main
info
Minecraft client 1.14.2 is ready to start.
17:19:26
launcher
main
info
Starting!
17:19:26
launcher
main
info
Using default game log configuration client-1.12.xml (outputs XML)
17:19:34
launcher
main
info
Error: Could not find or load main class net.minecraft.client.main.Main
17:19:34
monitor
Process Monitor
fatal
Process crashed with exit code 1