PluginRemapper is invasive to plugins! Can cause plugins to work improperly

[RegotlyLong]

Expected behavior

I wish PluginRemapper could be switched off in paper-global.yml or somewhere else, because in version 1.20.6 I found a lot of plugins being switched off due to problems caused by Remapper!

Observed/Actual behavior

[ModernPluginLoadingStrategy] Could not load plugin 'PlaceholderAPI.jar' in folder 'plugins.paper-remapped'
org.bukkit.plugin.InvalidPluginException: java.lang.ExceptionInInitializerError
at io.papermc.paper.plugin.provider.type.spigot.SpigotPluginProvider.createInstance(SpigotPluginProvider.java:127) ~[paper-1.20.6.jar:git-Paper-53]
at io.papermc.paper.plugin.provider.type.spigot.SpigotPluginProvider.createInstance(SpigotPluginProvider.java:35) ~[paper-1.20.6.jar:git-Paper-53]
at io.papermc.paper.plugin.entrypoint.strategy.modern.ModernPluginLoadingStrategy.loadProviders(ModernPluginLoadingStrategy.java:116) ~[paper-1.20.6.jar:git-Paper-53]
at io.papermc.paper.plugin.storage.SimpleProviderStorage.enter(SimpleProviderStorage.java:38) ~[paper-1.20.6.jar:git-Paper-53]
at io.papermc.paper.plugin.entrypoint.LaunchEntryPointHandler.enter(LaunchEntryPointHandler.java:36) ~[paper-1.20.6.jar:git-Paper-53]
at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:508) ~[paper-1.20.6.jar:git-Paper-53]
at net.minecraft.server.dedicated.DedicatedServer.initServer(DedicatedServer.java:287) ~[paper-1.20.6.jar:git-Paper-53]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1140) ~[paper-1.20.6.jar:git-Paper-53]
at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:326) ~[paper-1.20.6.jar:git-Paper-53]
at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]
Caused by: java.lang.ExceptionInInitializerError
at java.base/java.lang.Class.forName0(Native Method) ~[?:?]
at java.base/java.lang.Class.forName(Class.java:534) ~[?:?]
at java.base/java.lang.Class.forName(Class.java:513) ~[?:?]
at org.bukkit.plugin.java.PluginClassLoader.(PluginClassLoader.java:78) ~[paper-api-1.20.6-R0.1-SNAPSHOT.jar:?]
at io.papermc.paper.plugin.provider.type.spigot.SpigotPluginProvider.createInstance(SpigotPluginProvider.java:123) ~[paper-1.20.6.jar:git-Paper-53]
... 9 more
Caused by: java.lang.ArrayIndexOutOfBoundsException: Index 3 out of bounds for length 3
at PlaceholderAPI-2.11.3.jar/me.clip.placeholderapi.PlaceholderAPIPlugin.(PlaceholderAPIPlugin.java:58) ~[PlaceholderAPI-2.11.3.jar:?]
at java.base/java.lang.Class.forName0(Native Method) ~[?:?]
at java.base/java.lang.Class.forName(Class.java:534) ~[?:?]
at java.base/java.lang.Class.forName(Class.java:513) ~[?:?]
at org.bukkit.plugin.java.PluginClassLoader.(PluginClassLoader.java:78) ~[paper-api-1.20.6-R0.1-SNAPSHOT.jar:?]
at io.papermc.paper.plugin.provider.type.spigot.SpigotPluginProvider.createInstance(SpigotPluginProvider.java:123) ~[paper-1.20.6.jar:git-Paper-53]
... 9 more
[13:55:40 ERROR]: [ModernPluginLoadingStrategy] Could not load plugin 'LoaderLib.jar' in folder 'plugins.paper-remapped'
org.bukkit.plugin.InvalidPluginException: Cannot find main class `me.loader.Loader'
at org.bukkit.plugin.java.PluginClassLoader.(PluginClassLoader.java:80) ~[paper-api-1.20.6-R0.1-SNAPSHOT.jar:?]
at io.papermc.paper.plugin.provider.type.spigot.SpigotPluginProvider.createInstance(SpigotPluginProvider.java:123) ~[paper-1.20.6.jar:git-Paper-53]
at io.papermc.paper.plugin.provider.type.spigot.SpigotPluginProvider.createInstance(SpigotPluginProvider.java:35) ~[paper-1.20.6.jar:git-Paper-53]
at io.papermc.paper.plugin.entrypoint.strategy.modern.ModernPluginLoadingStrategy.loadProviders(ModernPluginLoadingStrategy.java:116) ~[paper-1.20.6.jar:git-Paper-53]
at io.papermc.paper.plugin.storage.SimpleProviderStorage.enter(SimpleProviderStorage.java:38) ~[paper-1.20.6.jar:git-Paper-53]
at io.papermc.paper.plugin.entrypoint.LaunchEntryPointHandler.enter(LaunchEntryPointHandler.java:36) ~[paper-1.20.6.jar:git-Paper-53]
at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:508) ~[paper-1.20.6.jar:git-Paper-53]
at net.minecraft.server.dedicated.DedicatedServer.initServer(DedicatedServer.java:287) ~[paper-1.20.6.jar:git-Paper-53]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1140) ~[paper-1.20.6.jar:git-Paper-53]
at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:326) ~[paper-1.20.6.jar:git-Paper-53]
at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]
Caused by: java.lang.ClassNotFoundException: me.loader.Loader
at org.bukkit.plugin.java.PluginClassLoader.loadClass0(PluginClassLoader.java:197) ~[paper-api-1.20.6-R0.1-SNAPSHOT.jar:?]
at org.bukkit.plugin.java.PluginClassLoader.loadClass(PluginClassLoader.java:164) ~[paper-api-1.20.6-R0.1-SNAPSHOT.jar:?]
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526) ~[?:?]
at java.base/java.lang.Class.forName0(Native Method) ~[?:?]
at java.base/java.lang.Class.forName(Class.java:534) ~[?:?]
at java.base/java.lang.Class.forName(Class.java:513) ~[?:?]
at org.bukkit.plugin.java.PluginClassLoader.(PluginClassLoader.java:78) ~[paper-api-1.20.6-R0.1-SNAPSHOT.jar:?]
... 10 more

Steps/models to reproduce

none

Plugin and Datapack List

none

Paper version

: This server is running Paper version git-Paper-53 (MC: 1.20.6) (Implementing API version 1.20.6-R0.1-SNAPSHOT) (Git: 5729b29)
Error obtaining version information

Other

none

[Machine-Maker]

Plugin & Datapack List
none

I find that really hard to believe seeing as the error provided is because of plugin loading.

[RegotlyLong]

Plugin & Datapack List
none

I find that really hard to believe seeing as the error provided is because of plugin loading.

[13:55:40 ERROR]: [ModernPluginLoadingStrategy] Could not load plugin 'LoaderLib.jar' in folder 'plugins.paper-remapped'
org.bukkit.plugin.InvalidPluginException: Cannot find main class `me.loader.Loader'
at org.bukkit.plugin.java.PluginClassLoader.(PluginClassLoader.java:80) ~[paper-api-1.20.6-R0.1-SNAPSHOT.jar:?]
at io.papermc.paper.plugin.provider.type.spigot.SpigotPluginProvider.createInstance(SpigotPluginProvider.java:123) ~[paper-1.20.6.jar:git-Paper-53]
at io.papermc.paper.plugin.provider.type.spigot.SpigotPluginProvider.createInstance(SpigotPluginProvider.java:35) ~[paper-1.20.6.jar:git-Paper-53]
at io.papermc.paper.plugin.entrypoint.strategy.modern.ModernPluginLoadingStrategy.loadProviders(ModernPluginLoadingStrategy.java:116) ~[paper-1.20.6.jar:git-Paper-53]
at io.papermc.paper.plugin.storage.SimpleProviderStorage.enter(SimpleProviderStorage.java:38) ~[paper-1.20.6.jar:git-Paper-53]
at io.papermc.paper.plugin.entrypoint.LaunchEntryPointHandler.enter(LaunchEntryPointHandler.java:36) ~[paper-1.20.6.jar:git-Paper-53]
at org.bukkit.craftbukkit.CraftServer.loadPlugins(CraftServer.java:508) ~[paper-1.20.6.jar:git-Paper-53]
at net.minecraft.server.dedicated.DedicatedServer.initServer(DedicatedServer.java:287) ~[paper-1.20.6.jar:git-Paper-53]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1140) ~[paper-1.20.6.jar:git-Paper-53]
at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:326) ~[paper-1.20.6.jar:git-Paper-53]
at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]
Caused by: java.lang.ClassNotFoundException: me.loader.Loader
at org.bukkit.plugin.java.PluginClassLoader.loadClass0(PluginClassLoader.java:197) ~[paper-api-1.20.6-R0.1-SNAPSHOT.jar:?]
at org.bukkit.plugin.java.PluginClassLoader.loadClass(PluginClassLoader.java:164) ~[paper-api-1.20.6-R0.1-SNAPSHOT.jar:?]
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526) ~[?:?]
at java.base/java.lang.Class.forName0(Native Method) ~[?:?]
at java.base/java.lang.Class.forName(Class.java:534) ~[?:?]
at java.base/java.lang.Class.forName(Class.java:513) ~[?:?]
at org.bukkit.plugin.java.PluginClassLoader.(PluginClassLoader.java:78) ~[paper-api-1.20.6-R0.1-SNAPSHOT.jar:?]
... 10 more

[RegotlyLong]

Plugin & Datapack List
none

I find that really hard to believe seeing as the error provided is because of plugin loading.

There are some plug-ins that will lead to a lack of class files after being remapper, this problem will be very serious, not only will lead to the MD5 file has been modified, but also may make the plug-in author think that you may be in the magic of his plug-ins, and some plug-ins are not allowed to be remapper, be removed will be less class files.

[electronicboy]

You can disable plugin remapping by adding -Dpaper.disable-plugin-rewriting=true to your JVM args, however, this will break any plugins which are using internals which haven't been adopted specifically for paper

if the remapper is breaking stuff, then we'd generally like to be able to have the means to reproduce and investigate this stuff

[lynxplay]

Please provide a minimal replication plugin for your issue ^
We cannot debug failures of unknown plugins.

[RegotlyLong]

Please provide a minimal replication plugin for your issue ^ We cannot debug failures of unknown plugins.
How can I send it to you?

[lynxplay]

Presumably have the plugin be open source (e.g. here on github) or provide the jar as is.

[Malfrador]

PlaceholderAPI is parsing the Craftbukkit package to determine the Minecraft version. However, Craftbukkit package relocation has been removed in recent versions of Paper, so this no longer works. This has been anounced quite a while ago so there was sufficient time to prepare for this change.
PlaceholderAPI has already updated to support this. You currently need to use the dev builds, which you can download here. Using the dev build, PAPI loads fine on latest Paper 1.20.6

I am unable to find "LoaderLib" anywhere online, only a Fabric mod of the same name. We would need that plugin to reproduce the issue. If you don't want to post it publicly, you can also send it privately on the Paper Discord using /modmail.

[RegotlyLong]

The problem arises when plugins are obfuscated, and it is possible that an obfuscated plugin may not be remapper, which is why it causes noclassfound

[RegotlyLong]

If possible, it is recommended that the paper's config can be added to turn off the remapper by default.

[kennytv]

If a plugin wishes to not be remapped (and actually runs on a Mojang mapped server!), it can mark itself as such https://docs.papermc.io/paper/dev/userdev#1205