diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0e6ba844..2f1de46c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -54,6 +54,7 @@
   * Fix passing `format` option to `devise_for` [#5732](https://github.com/heartcombo/devise/pull/5732)
   * Use `ActiveRecord::SecurityUtils.secure_compare` in `Devise.secure_compare` to match two empty strings correctly. [#4829](https://github.com/heartcombo/devise/pull/4829)
   * Respond with `401 Unauthorized` for non-navigational requests to destroy the session when there is no authenticated resource. [#4878](https://github.com/heartcombo/devise/pull/4878)
+  * Fix incorrect grammar of invalid authentication message with capitalized attributes, e.g.: "Invalid Email or password" => "Invalid email or password". (originally introduced by [#4014](https://github.com/heartcombo/devise/pull/4014), released on v4.1.0) [#4834](https://github.com/heartcombo/devise/pull/4834)
 
 
 Please check [4-stable](https://github.com/heartcombo/devise/blob/4-stable/CHANGELOG.md)
diff --git a/lib/devise/failure_app.rb b/lib/devise/failure_app.rb
index 2f3e11e5..8222780f 100644
--- a/lib/devise/failure_app.rb
+++ b/lib/devise/failure_app.rb
@@ -111,13 +111,16 @@ module Devise
         options[:scope] = "devise.failure"
         options[:default] = [message]
         auth_keys = scope_class.authentication_keys
-        keys = (auth_keys.respond_to?(:keys) ? auth_keys.keys : auth_keys).map { |key| scope_class.human_attribute_name(key).downcase }
-        options[:authentication_keys] = keys.join(I18n.t(:"support.array.words_connector"))
+        human_keys = (auth_keys.respond_to?(:keys) ? auth_keys.keys : auth_keys).map { |key|
+          scope_class.human_attribute_name(key).downcase
+        }
+        options[:authentication_keys] = human_keys.join(I18n.t(:"support.array.words_connector"))
         options = i18n_options(options)
-        translated_message = I18n.t(:"#{scope}.#{message}", **options)
-        # only call `#humanize` when the message is `:invalid` to ensure the original format
-        # of other messages - like `:does_not_exist` - is kept.
-        message == :invalid ? translated_message.humanize : translated_message
+
+        I18n.t(:"#{scope}.#{message}", **options).then { |msg|
+          # Ensure that auth keys at the start of the translated string are properly cased.
+          msg.start_with?(human_keys.first) ? msg.upcase_first : msg
+        }
       else
         message.to_s
       end