AGM Rank Error at boot on 1.17.1 server

[21:42:49] [Server thread/WARN]: Legacy plugin AGMRanks v4.1.0 does not specify an api-version.
[21:42:49] [Server thread/ERROR]: Could not load 'plugins/AGMRanks-4.1.0.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.NoClassDefFoundError: me/ashenguard/api/spigot/SpigotPlugin
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:157) ~[patched_1.17.1.jar:git-Purpur-1394]
    at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:414) ~[patched_1.17.1.jar:git-Purpur-1394]
    at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:322) ~[patched_1.17.1.jar:git-Purpur-1394]
    at org.bukkit.craftbukkit.v1_17_R1.CraftServer.loadPlugins(CraftServer.java:410) ~[patched_1.17.1.jar:git-Purpur-1394]
    at net.minecraft.server.dedicated.DedicatedServer.init(DedicatedServer.java:287) ~[patched_1.17.1.jar:git-Purpur-1394]
    at net.minecraft.server.MinecraftServer.x(MinecraftServer.java:1216) ~[patched_1.17.1.jar:git-Purpur-1394]
    at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:321) ~[patched_1.17.1.jar:git-Purpur-1394]
    at java.lang.Thread.run(Thread.java:831) [?:?]
Caused by: java.lang.NoClassDefFoundError: me/ashenguard/api/spigot/SpigotPlugin
    at java.lang.ClassLoader.defineClass1(Native Method) ~[?:?]
    at java.lang.ClassLoader.defineClass(ClassLoader.java:1010) ~[?:?]
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:150) ~[?:?]
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:195) ~[patched_1.17.1.jar:git-Purpur-1394]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:586) ~[?:?]
    at org.bukkit.plugin.java.PluginClassLoader.loadClass0(PluginClassLoader.java:110) ~[patched_1.17.1.jar:git-Purpur-1394]
    at org.bukkit.plugin.java.PluginClassLoader.loadClass(PluginClassLoader.java:105) ~[patched_1.17.1.jar:git-Purpur-1394]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:519) ~[?:?]
    at java.lang.Class.forName0(Native Method) ~[?:?]
    at java.lang.Class.forName(Class.java:466) ~[?:?]
    at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:73) ~[patched_1.17.1.jar:git-Purpur-1394]
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:153) ~[patched_1.17.1.jar:git-Purpur-1394]
    ... 7 more
Caused by: java.lang.ClassNotFoundException: me.ashenguard.api.spigot.SpigotPlugin
    at org.bukkit.plugin.java.PluginClassLoader.loadClass0(PluginClassLoader.java:148) ~[patched_1.17.1.jar:git-Purpur-1394]
    at org.bukkit.plugin.java.PluginClassLoader.loadClass(PluginClassLoader.java:105) ~[patched_1.17.1.jar:git-Purpur-1394]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:519) ~[?:?]
    at java.lang.ClassLoader.defineClass1(Native Method) ~[?:?]
    at java.lang.ClassLoader.defineClass(ClassLoader.java:1010) ~[?:?]
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:150) ~[?:?]
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:195) ~[patched_1.17.1.jar:git-Purpur-1394]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:586) ~[?:?]
    at org.bukkit.plugin.java.PluginClassLoader.loadClass0(PluginClassLoader.java:110) ~[patched_1.17.1.jar:git-Purpur-1394]
    at org.bukkit.plugin.java.PluginClassLoader.loadClass(PluginClassLoader.java:105) ~[patched_1.17.1.jar:git-Purpur-1394]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:519) ~[?:?]
    at java.lang.Class.forName0(Native Method) ~[?:?]
    at java.lang.Class.forName(Class.java:466) ~[?:?]
    at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:73) ~[patched_1.17.1.jar:git-Purpur-1394]
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:153) ~[patched_1.17.1.jar:git-Purpur-1394]
    ... 7 more