[14:17:20.526 [main] ERROR FabricLoader - Could not find valid game provider! Exception in thread "main" java.lang.NullPointerException at net.fabricmc.loader.game.MinecraftGameProvider.getRawGameVersion(MinecraftGameProvider.java:70) at net.fabricmc.loader.launch.knot.Knot.init(Knot.java:93) at net.fabricmc.loader.launch.knot.KnotClient.main(KnotClient.java:26)](url)

How can I solve this problem????

Looks just like FabricMC/fabric-loader#197. Update loader, and open new issue in loader repo if the problem persists.