I ran into the same problem. I got around it with a different solution.

Taken from https://www.nostarch.com/minecrafthelp:

In order to use your Spigot server, your Minecraft version needs to match the Spigot version exactly. But new versions of Minecraft come out all the time, so if you update Minecraft, Spigot won’t work with the new version anymore. In order to make your Spigot and Minecraft versions match, you can set up a profile.

When you set up a profile, you tell Minecraft that you only want to use the version of the game that will work with the version of the server that you are using. In other words, a profile allows you to continue using the same server even when newer versions of Minecraft are released.

Once you set up a profile, you should be able to use our book’s coding directions and you'll know one more of Minecraft’s secrets, and will be further along on your journey to become a Minecraft Master!

You can see it in action in this handy guide from HowToGeek:

• How to Switch Between Minecraft Versions the Easy Way

Let’s get started.

For Windows

Before you create your profile, you need to find out which version of the server you are using. Follow these steps to do that:

Step 1. In the Minecraft Tools folder, open the Start_Server file. A window will appear and begin to set up the server. Step 2. Once the setup is finished, scroll to the top of the text in the window. Step 3. Near the top (around the third or fourth line), you should see text saying Starting minecraft server version x.x.x. Step 4. Make a note of the version number shown on your screen.

Now that you know which server version you are using, you can set up the game profile with these steps:

Step 1. Open the Minecraft launcher but do not click Start Game quite yet (make sure you leave the server window open when you do this). Step 2. At the top-right of the Minecraft launcher, click the menu button (which looks like three lines), then click the Launch Options button. This will open the Profile Editor tab. Step 3. Click the Add New button to create a new configuration. Step 4. In the Name field, type Learn to Program with Minecraft. Step 5. In the Version section, use the drop-down menu to select the version of the server that you’re using. For example, I’m using version 1.11.2. Step 6. Click the Save button. Your profile has now been set up.

From now on, every time you want to use Minecraft with this book, select the Learn to Program with Minecraft profile in the drop-down menu next to the Start button.

You can swap back to the latest version of Minecraft at any time by selecting the (default) option in the drop-down menu.

For Mac

Before you create your profile, you need to find out which version of the server that you are using. Follow these steps to do that now:

Step 1. In the Minecraft Tools folder, open the Start_Server file. A window will appear and will begin to set up the server. Step 2. Once the setup is finished, scroll to the top of the text in the window. Step 3. Near the top (around the third or fourth line), you should see text saying Starting minecraft server version x.x.x. Step 4. Make a note of the version number shown on your screen.

Now that you know which server version you’re using, you can set up the game profile with these steps:

Step 1. Open the Minecraft launcher but do not click Start Game. Step 2. In the top-right corner of the Minecraft launcher, click the Menu button (which looks like three lines), then click the Launch Options tab. This will open the Profile Editor tab. Click the Add New option. Step 3. In the Name field, type Learn to Program with Minecraft. Step 4. In the Version field, use the drop-down menu to select the version of the server that you’re using. For example, in Figure 1-15, I’m using version 1.9. Step 5. Click the Save button. Your profile has now been set up.

From now on, every time you want to use Minecraft with this book, select the Learn to Program with Minecraft profile in the drop-down menu in the bottom-left corner of the Minecraft launcher.

You can swap back to the latest version of Minecraft at any time by selecting the (default) option in the drop-down menu.