Wrap Rack parameter parsing errors in Grape::Exceptions::RequestError

Replace five specific exception classes (EmptyMessageBody, TooManyMultipartFiles,
TooDeepParameters, ConflictingTypes, InvalidParameters) with a single
Grape::Exceptions::RequestError that forwards the Rack exception message directly.

On Rack 3, a single `rescue Rack::BadRequest` covers all bad-request errors via
the marker module. On Rack 2, each exception class is listed explicitly in
Grape::RACK_ERRORS.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ericproulx

UPGRADING.md

@@ -3,6 +3,24 @@ Upgrading Grape
 
 ### Upgrading to >= 3.2
 
+#### Rack parameter parsing errors now raise `Grape::Exceptions::RequestError`
+
+Rack errors raised during parameter parsing (malformed multipart, parameter type conflicts, encoding issues, etc.) are now wrapped in `Grape::Exceptions::RequestError` instead of their previous specific exception classes (`Grape::Exceptions::EmptyMessageBody`, `Grape::Exceptions::TooManyMultipartFiles`, `Grape::Exceptions::TooDeepParameters`, `Grape::Exceptions::ConflictingTypes`, `Grape::Exceptions::InvalidParameters`). Those classes have been removed.
+
+If you rescue any of these specific exceptions, update your rescue clauses to use `Grape::Exceptions::RequestError`:
+
+```ruby
+# Before
+rescue Grape::Exceptions::ConflictingTypes, Grape::Exceptions::TooDeepParameters => e
+  # ...
+
+# After
+rescue Grape::Exceptions::RequestError => e
+  # ...
+```
+
+The error message is now forwarded directly from Rack rather than translated through Grape's locale system. On Rack 3, all Rack bad-request errors share the `Rack::BadRequest` marker module and are covered by a single rescue.
+
 #### `endpoint_run_validators.grape` notification no longer fired when there are no validators
 
 `ActiveSupport::Notifications` subscribers listening to `endpoint_run_validators.grape` will no longer receive an event for endpoints that have no validators. If you rely on this notification to measure every request, subscribe to `endpoint_run.grape` instead, which always fires.

lib/grape.rb

@@ -63,6 +63,24 @@ module Grape
     Rack::OPTIONS
   ].freeze
 
+  # Rack errors that should be rescued and wrapped as Grape::Exceptions::RequestError.
+  # Rack 3 introduced Rack::BadRequest as a marker module included by all bad request
+  # exception classes, allowing a single rescue entry to cover them all.
+  # On Rack 2, these errors are raised as individual exception classes.
+  RACK_ERRORS =
+    if defined?(Rack::BadRequest)
+      [EOFError, Rack::BadRequest]
+    else
+      [
+        EOFError,
+        Rack::Multipart::MultipartPartLimitError,
+        Rack::Multipart::MultipartTotalPartLimitError,
+        Rack::Utils::ParameterTypeError,
+        Rack::Utils::InvalidParameterError,
+        Rack::QueryParser::ParamsTooDeepError
+      ]
+    end.freeze
+
   def self.deprecator
     @deprecator ||= ActiveSupport::Deprecation.new('2.0', 'Grape')
   end

lib/grape/exceptions/conflicting_types.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+module Grape
+  module Exceptions
+    class RequestError < Base
+      def initialize(exception, status: 400)
+        super(message: exception.message, status: status)
+      end
+    end
+  end
+end

lib/grape/exceptions/empty_message_body.rb

@@ -8,8 +8,6 @@ en:
         at_least_one: 'are missing, at least one parameter must be provided'
         blank: 'is empty'
         coerce: 'is invalid'
-        conflicting_types: 'query params contains conflicting types'
-        empty_message_body: 'empty message body supplied with %{body_format} content-type'
         exactly_one: 'are missing, exactly one parameter must be provided'
         except_values: 'has a value not allowed'
         incompatible_option_values: '%{option1}: %{value1} is incompatible with %{option2}: %{value2}'
@@ -20,7 +18,6 @@ en:
         invalid_message_body:
           problem: 'message body does not match declared format'
           resolution: 'when specifying %{body_format} as content-type, you must pass valid %{body_format} in the request''s ''body'' '
-        invalid_parameters: 'query params contains invalid format or byte sequence'
         invalid_response: 'Invalid response'
         invalid_version_header:
           problem: 'invalid version header'
@@ -48,8 +45,6 @@ en:
         presence: 'is missing'
         regexp: 'is invalid'
         same_as: 'is not the same as %{parameter}'
-        too_deep_parameters: 'query params are recursively nested over the specified limit (%{limit})'
-        too_many_multipart_files: 'the number of uploaded files exceeded the system''s configured limit (%{limit})'
         unknown_auth_strategy: 'unknown auth strategy: %{strategy}'
         unknown_options: 'unknown options: %{options}'
         unknown_parameter: 'unknown parameter: %{param}'

lib/grape/exceptions/invalid_parameters.rb

@@ -79,10 +79,8 @@ def content_type
 
       def query_params
         rack_request.GET
-      rescue Rack::QueryParser::ParamsTooDeepError
-        raise Grape::Exceptions::TooDeepParameters.new(Rack::Utils.param_depth_limit)
-      rescue Rack::Utils::ParameterTypeError
-        raise Grape::Exceptions::ConflictingTypes
+      rescue *Grape::RACK_ERRORS => e
+        raise Grape::Exceptions::RequestError.new(e)
       end
 
       private