In this article I will show you how you can update the Minecraft version on your Minecraft server.
Here you can find server files.
Vanilla: https://getbukkit.org/download/vanilla
Spigot: https://getbukkit.org/download/spigot
CraftBukkit: https://getbukkit.org/download/craftbukkit
*You can download the versions from the links.
1. First download the version you want. I will be downloading the Vanilla 1.8 version.
2. When you have installed the .jar file to your computer, go into Pterodactyl control panel and drag the file on the "Files" tab.
3. The new .jar file will replace the old one so the game world will regenerate.
4. To apply these changes restart the server. You can restart your server from the "Console" tab.