diff --git a/discord/client.py b/discord/client.py
index 1d3cd5ec..f9a1d9e6 100644
--- a/discord/client.py
+++ b/discord/client.py
@@ -615,6 +615,8 @@ class Client:
 
         To perform asynchronous setup after the bot is logged in but before
         it has connected to the Websocket, overwrite this coroutine.
+
+        .. versionadded:: 2.0
         """
         pass
 
@@ -706,7 +708,7 @@ class Client:
         """:class:`.Status`:
         The status being used upon logging on to Discord.
 
-        .. versionadded: 2.0
+        .. versionadded:: 2.0
         """
         if self._connection._status in set(state.value for state in Status):
             return Status(self._connection._status)
diff --git a/discord/ext/commands/bot.py b/discord/ext/commands/bot.py
index bb8234cb..8d19592c 100644
--- a/discord/ext/commands/bot.py
+++ b/discord/ext/commands/bot.py
@@ -1128,6 +1128,24 @@ class BotBase(GroupMixin):
 
 
     async def process_slash_commands(self, interaction: discord.Interaction):
+        """|coro|
+
+        This function processes a slash command interaction into a usable
+        message and calls :meth:`.process_commands` based on it. Without this
+        coroutine slash commands will not be triggered.
+
+        By default, this coroutine is called inside the :func:`.on_interaction`
+        event. If you choose to override the :func:`.on_interaction` event,
+        then you should invoke this coroutine as well.
+
+        .. versionadded:: 2.0
+
+        Parameters
+        -----------
+        interaction: :class:`discord.Interaction`
+            The interaction to process slash commands for.
+
+        """
         interaction.data = cast(ApplicationCommandInteractionData, interaction.data)
         command_name, command_options = _unwrap_slash_groups(interaction.data)
 
@@ -1164,7 +1182,6 @@ class BotBase(GroupMixin):
                     raise errors.MissingRequiredArgument(param)
             elif (
                 option["type"] == 3
-                and " " in option["value"] # type: ignore
                 and param.kind != param.KEYWORD_ONLY
                 and not isinstance(param.annotation, Greedy)
             ):
diff --git a/discord/ext/commands/converter.py b/discord/ext/commands/converter.py
index 7d46b693..0545ead7 100644
--- a/discord/ext/commands/converter.py
+++ b/discord/ext/commands/converter.py
@@ -586,7 +586,7 @@ class ThreadConverter(IDConverter[discord.Thread]):
     2. Lookup by mention.
     3. Lookup by name.
 
-    .. versionadded: 2.0
+    .. versionadded:: 2.0
     """
 
     async def convert(self, ctx: Context, argument: str) -> discord.Thread:
diff --git a/discord/ext/commands/core.py b/discord/ext/commands/core.py
index b5eef841..6bca3f31 100644
--- a/discord/ext/commands/core.py
+++ b/discord/ext/commands/core.py
@@ -1187,7 +1187,7 @@ class Command(_BaseCommand, Generic[CogT, P, T]):
         if self.slash_command is False:
             return
         elif nested == 3:
-            raise ValueError(f"{self.qualified_name} is too deeply nested!")
+            raise ApplicationCommandRegistrationError(self, f"{self.qualified_name} is too deeply nested!")
 
         payload = {
             "name": self.name,
@@ -1208,7 +1208,7 @@ class Command(_BaseCommand, Generic[CogT, P, T]):
             option: Dict[str, Any] = {
                 "name": name,
                 "description": self.option_descriptions[name],
-                "required": param.default is param.empty and not self._is_typing_optional(annotation),
+                "required": (param.default is param.empty and not self._is_typing_optional(annotation)) or param.kind == param.VAR_POSITIONAL,
             }
 
             annotation = cast(Any, annotation)
@@ -1616,7 +1616,7 @@ class Group(GroupMixin[CogT], Command[CogT, P, T]):
         if self.slash_command is False:
             return
         elif nested == 2:
-            raise ValueError(f"{self.qualified_name} is too deeply nested for slash commands!")
+            raise ApplicationCommandRegistrationError(self, f"{self.qualified_name} is too deeply nested!")
 
         return { # type: ignore
             "name": self.name,
diff --git a/discord/ext/commands/errors.py b/discord/ext/commands/errors.py
index 01dbaee2..a150b215 100644
--- a/discord/ext/commands/errors.py
+++ b/discord/ext/commands/errors.py
@@ -930,9 +930,9 @@ class ApplicationCommandRegistrationError(ClientException):
     command: :class:`Command`
         The command that failed to be converted.
     """
-    def __init__(self, command: Command) -> None:
+    def __init__(self, command: Command, msg: str = None) -> None:
         self.command = command
-        super().__init__(f"{command.qualified_name} failed to converted to an application command.")
+        super().__init__(msg or f"{command.qualified_name} failed to converted to an application command.")
 
 class FlagError(BadArgument):
     """The base exception type for all flag parsing related errors.