It's not really something wrong with it, but I suppose the mechanic is a bit unclear and poorly done on my part. The <Target Barrier x Turns: -y> targets the barrier points at exactly turn x. Since each turn, the barrier points shift downward, your 3 turn barrier cast by the enemy becomes a 2 turn barrier and so on. However, it seems that even with that as my intention, the mechanic isn't working properly. I'll have to see what's going on with this tonight.
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BASIC TROUBLE SHOOTING
1. Are all your plugins up to date? If they're not, download the updated versions from here:
http://yanfly.moe/yep/changelog/
2. Did you rename any of their plugins from their default filenames? If you did, then the plugins won't work. Do NOT rename them.
3. Did you make sure all of the plugins are placed in order as
http://yanfly.moe/yep/ inside of the Plugin Manager?
4. When you updated the plugin, did you /open up/ the plugin within the Plugin Manager?
You are getting the error because you updated the plugin and did not go into the plugin itself like the instructions here in the first video:
http://yanfly.moe/yep/changelog/
Why is this important? Because whenever new parameters are added to a plugin upon a new update, you have to enter the plugin in order for the Plugin Manager to add those new parameters into your game. Otherwise, you will get undefined errors and "random" crashes. Skipping that step is not optional and is very crucial to getting updated plugins to work.
5. If you are using non-Yanfly plugins, turn off ALL of the non-Yanfly plugins to see if there are any conflicts.
6. If you are testing your project in Battle Test and aren't seeing any changes made after updating your plugin, make sure you -save- your project. RPG Maker MV does not carry over changes to Battle Test until you save your project.