diff --git a/application/models/Admins_model.php b/application/models/Admins_model.php
index 0740e53b..07ad12f5 100644
--- a/application/models/Admins_model.php
+++ b/application/models/Admins_model.php
@@ -60,7 +60,7 @@ class Admins_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function validate(array $admin): void
+    public function validate(array $admin)
     {
         // If an admin ID is provided then check whether the record really exists in the database.
         if ( ! empty($admin['id']))
@@ -237,7 +237,7 @@ class Admins_model extends EA_Model {
      *
      * @throws RuntimeException
      */
-    public function delete(int $admin_id): void
+    public function delete(int $admin_id)
     {
         $role_id = $this->get_admin_role_id();
 
@@ -389,7 +389,7 @@ class Admins_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    protected function save_settings(int $admin_id, array $settings): void
+    protected function save_settings(int $admin_id, array $settings)
     {
         if (empty($settings))
         {
@@ -417,7 +417,7 @@ class Admins_model extends EA_Model {
      * @param string $name Setting name.
      * @param string $value Setting value.
      */
-    public function set_setting(int $admin_id, string $name, string $value): void
+    public function set_setting(int $admin_id, string $name, string $value)
     {
         if ( ! $this->db->update('user_settings', [$name => $value], ['id_users' => $admin_id]))
         {
@@ -501,7 +501,7 @@ class Admins_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function attach(array &$admin, array $resources): void
+    public function attach(array &$admin, array $resources)
     {
         // Admins do not currently have any related resources (settings are already part of the admins). 
     }
diff --git a/application/models/Appointments_model.php b/application/models/Appointments_model.php
index a43db8b0..ea55d024 100644
--- a/application/models/Appointments_model.php
+++ b/application/models/Appointments_model.php
@@ -58,7 +58,7 @@ class Appointments_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function validate(array $appointment): void
+    public function validate(array $appointment)
     {
         // If an appointment ID is provided then check whether the record really exists in the database.
         if ( ! empty($appointment['id']))
@@ -195,7 +195,7 @@ class Appointments_model extends EA_Model {
      *
      * @throws RuntimeException
      */
-    public function delete(int $appointment_id): void
+    public function delete(int $appointment_id)
     {
         if ( ! $this->db->delete('users', ['id' => $appointment_id]))
         {
@@ -355,7 +355,7 @@ class Appointments_model extends EA_Model {
      *
      * @param int $provider_id Matching provider ID.
      */
-    public function clear_google_sync_ids(int $provider_id): void
+    public function clear_google_sync_ids(int $provider_id)
     {
         $this->db->update('appointments', ['id_google_calendar' => NULL], ['id_users_provider' => $provider_id]);
     }
@@ -500,7 +500,7 @@ class Appointments_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function attach(array &$appointment, array $resources): void
+    public function attach(array &$appointment, array $resources)
     {
         if (empty($appointment) || empty($resources))
         {
diff --git a/application/models/Consents_model.php b/application/models/Consents_model.php
index 94f0c3cd..1f597520 100644
--- a/application/models/Consents_model.php
+++ b/application/models/Consents_model.php
@@ -50,7 +50,7 @@ class Consents_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function validate(array $consent): void
+    public function validate(array $consent)
     {
         if (
             empty($consent['first_name'])
@@ -114,7 +114,7 @@ class Consents_model extends EA_Model {
      *
      * @throws RuntimeException
      */
-    public function delete(int $consent_id): void
+    public function delete(int $consent_id)
     {
         if ( ! $this->db->delete('consents', ['id' => $consent_id]))
         {
@@ -252,7 +252,7 @@ class Consents_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function attach(array &$consent, array $resources): void
+    public function attach(array &$consent, array $resources)
     {
         // Consents do not currently have any related resources. 
     }
diff --git a/application/models/Customers_model.php b/application/models/Customers_model.php
index 8e1ab1c0..926f79b3 100644
--- a/application/models/Customers_model.php
+++ b/application/models/Customers_model.php
@@ -54,7 +54,7 @@ class Customers_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function validate(array $customer): void
+    public function validate(array $customer)
     {
         // If a customer ID is provided then check whether the record really exists in the database.
         if ( ! empty($customer['id']))
@@ -153,7 +153,7 @@ class Customers_model extends EA_Model {
      *
      * @throws RuntimeException
      */
-    public function delete(int $customer_id): void
+    public function delete(int $customer_id)
     {
         if ( ! $this->db->delete('users', ['id' => $customer_id]))
         {
@@ -384,7 +384,7 @@ class Customers_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function attach(array &$customer, array $resources): void
+    public function attach(array &$customer, array $resources)
     {
         // Customers do not currently have any related resources. 
     }
diff --git a/application/models/Providers_model.php b/application/models/Providers_model.php
index 2b145de9..eb7edee1 100755
--- a/application/models/Providers_model.php
+++ b/application/models/Providers_model.php
@@ -60,7 +60,7 @@ class Providers_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function validate(array $provider): void
+    public function validate(array $provider)
     {
         // If a provider ID is provided then check whether the record really exists in the database.
         if ( ! empty($provider['id']))
@@ -261,7 +261,7 @@ class Providers_model extends EA_Model {
      *
      * @throws RuntimeException
      */
-    public function delete(int $provider_id): void
+    public function delete(int $provider_id)
     {
         if ( ! $this->db->delete('users', ['id' => $provider_id]))
         {
@@ -419,7 +419,7 @@ class Providers_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    protected function save_settings(int $provider_id, array $settings): void
+    protected function save_settings(int $provider_id, array $settings)
     {
         if (empty($settings))
         {
@@ -462,7 +462,7 @@ class Providers_model extends EA_Model {
      * @param string $name Setting name.
      * @param string $value Setting value.
      */
-    public function set_setting(int $provider_id, string $name, string $value): void
+    public function set_setting(int $provider_id, string $name, string $value)
     {
         if ( ! $this->db->update('user_settings', [$name => $value], ['id_users' => $provider_id]))
         {
@@ -496,7 +496,7 @@ class Providers_model extends EA_Model {
      * @param int $provider_id Provider ID.
      * @param array $service_ids Service IDs.
      */
-    protected function save_service_ids(int $provider_id, array $service_ids): void
+    protected function save_service_ids(int $provider_id, array $service_ids)
     {
         // Re-insert the provider-service connections. 
         $this->db->delete('services_providers', ['id_users' => $provider_id]);
@@ -521,7 +521,7 @@ class Providers_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function save_working_plan_exception(int $provider_id, string $date, array $working_plan_exception): void
+    public function save_working_plan_exception(int $provider_id, string $date, array $working_plan_exception)
     {
         // Validate the working plan exception data.
         $start = date('H:i', strtotime($working_plan_exception['start']));
@@ -569,7 +569,7 @@ class Providers_model extends EA_Model {
      *
      * @throws Exception If $provider_id argument is invalid.
      */
-    public function delete_working_plan_exception(int $provider_id, string $date): void
+    public function delete_working_plan_exception(int $provider_id, string $date)
     {
         $provider = $this->find($provider_id);
 
@@ -686,7 +686,7 @@ class Providers_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function attach(array &$provider, array $resources): void
+    public function attach(array &$provider, array $resources)
     {
         if (empty($provider) || empty($resources))
         {
diff --git a/application/models/Roles_model.php b/application/models/Roles_model.php
index 8b5f8005..5eaf584a 100644
--- a/application/models/Roles_model.php
+++ b/application/models/Roles_model.php
@@ -49,7 +49,7 @@ class Roles_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function validate(array $role): void
+    public function validate(array $role)
     {
         // If a role ID is provided then check whether the record really exists in the database.
         if ( ! empty($role['id']))
@@ -116,7 +116,7 @@ class Roles_model extends EA_Model {
      *
      * @throws RuntimeException
      */
-    public function delete(int $role_id): void
+    public function delete(int $role_id)
     {
         if ( ! $this->db->delete('roles', ['id' => $role_id]))
         {
@@ -318,7 +318,7 @@ class Roles_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function attach(array &$role, array $resources): void
+    public function attach(array &$role, array $resources)
     {
         // Roles do not currently have any related resources. 
     }
diff --git a/application/models/Secretaries_model.php b/application/models/Secretaries_model.php
index 1c4b7821..a6f4b5b5 100644
--- a/application/models/Secretaries_model.php
+++ b/application/models/Secretaries_model.php
@@ -60,7 +60,7 @@ class Secretaries_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function validate(array $secretary): void
+    public function validate(array $secretary)
     {
         // If a secretary ID is provided then check whether the record really exists in the database.
         if ( ! empty($provider['id']))
@@ -262,7 +262,7 @@ class Secretaries_model extends EA_Model {
      *
      * @throws RuntimeException
      */
-    public function delete(int $secretary_id): void
+    public function delete(int $secretary_id)
     {
         if ( ! $this->db->delete('users', ['id' => $secretary_id]))
         {
@@ -423,7 +423,7 @@ class Secretaries_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    protected function save_settings(int $secretary_id, array $settings): void
+    protected function save_settings(int $secretary_id, array $settings)
     {
         if (empty($settings))
         {
@@ -451,7 +451,7 @@ class Secretaries_model extends EA_Model {
      * @param string $name Setting name.
      * @param string $value Setting value.
      */
-    public function set_setting(int $secretary_id, string $name, string $value): void
+    public function set_setting(int $secretary_id, string $name, string $value)
     {
         if ( ! $this->db->update('user_settings', [$name => $value], ['id_users' => $secretary_id]))
         {
@@ -485,7 +485,7 @@ class Secretaries_model extends EA_Model {
      * @param int $secretary_id Secretary ID.
      * @param array $provider_ids Provider IDs.
      */
-    protected function save_provider_ids(int $secretary_id, array $provider_ids): void
+    protected function save_provider_ids(int $secretary_id, array $provider_ids)
     {
         // Re-insert the secretary-provider connections. 
         $this->db->delete('secretary_providers', ['id_users_secretary' => $secretary_id]);
@@ -557,7 +557,7 @@ class Secretaries_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function attach(array &$secretary, array $resources): void
+    public function attach(array &$secretary, array $resources)
     {
         if (empty($secretary) || empty($resources))
         {
diff --git a/application/models/Service_categories_model.php b/application/models/Service_categories_model.php
index 3641be91..9ff8dd13 100644
--- a/application/models/Service_categories_model.php
+++ b/application/models/Service_categories_model.php
@@ -49,7 +49,7 @@ class Service_categories_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function validate(array $service_category): void
+    public function validate(array $service_category)
     {
         // If a service category ID is provided then check whether the record really exists in the database.
         if ( ! empty($service_category['id']))
@@ -116,7 +116,7 @@ class Service_categories_model extends EA_Model {
      *
      * @throws RuntimeException
      */
-    public function delete(int $service_category_id): void
+    public function delete(int $service_category_id)
     {
         if ( ! $this->db->delete('service_categories', ['id' => $service_category_id]))
         {
@@ -252,7 +252,7 @@ class Service_categories_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function attach(array &$service_category, array $resources): void
+    public function attach(array &$service_category, array $resources)
     {
         // Service categories do not currently have any related resources. 
     }
diff --git a/application/models/Services_model.php b/application/models/Services_model.php
index 335ed023..cb0559c3 100644
--- a/application/models/Services_model.php
+++ b/application/models/Services_model.php
@@ -49,7 +49,7 @@ class Services_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function validate(array $service): void
+    public function validate(array $service)
     {
         // If a service ID is provided then check whether the record really exists in the database.
         if ( ! empty($service['id']))
@@ -159,7 +159,7 @@ class Services_model extends EA_Model {
      *
      * @throws RuntimeException
      */
-    public function delete(int $service_id): void
+    public function delete(int $service_id)
     {
         if ( ! $this->db->delete('services', ['id' => $service_id]))
         {
@@ -314,7 +314,7 @@ class Services_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function attach(array &$service, array $resources): void
+    public function attach(array &$service, array $resources)
     {
         if (empty($service) || empty($resources))
         {
diff --git a/application/models/Settings_model.php b/application/models/Settings_model.php
index 4fbc0711..b2a2f85e 100644
--- a/application/models/Settings_model.php
+++ b/application/models/Settings_model.php
@@ -49,7 +49,7 @@ class Settings_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function validate(array $setting): void
+    public function validate(array $setting)
     {
         // If a setting ID is provided then check whether the record really exists in the database.
         if ( ! empty($setting['id']))
@@ -116,7 +116,7 @@ class Settings_model extends EA_Model {
      *
      * @throws RuntimeException
      */
-    public function delete(int $setting_id): void
+    public function delete(int $setting_id)
     {
         if ( ! $this->db->delete('settings', ['id' => $setting_id]))
         {
@@ -252,7 +252,7 @@ class Settings_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function attach(array &$setting, array $resources): void
+    public function attach(array &$setting, array $resources)
     {
         // Users do not currently have any related resources. 
     }
diff --git a/application/models/Users_model.php b/application/models/Users_model.php
index 9e0dd69f..4efea351 100644
--- a/application/models/Users_model.php
+++ b/application/models/Users_model.php
@@ -49,7 +49,7 @@ class Users_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function validate(array $user): void
+    public function validate(array $user)
     {
         // If a user ID is provided then check whether the record really exists in the database.
         if ( ! empty($user['id']))
@@ -145,7 +145,7 @@ class Users_model extends EA_Model {
      *
      * @throws RuntimeException
      */
-    public function delete(int $user_id): void
+    public function delete(int $user_id)
     {
         if ( ! $this->db->delete('users', ['id' => $user_id]))
         {
@@ -265,7 +265,7 @@ class Users_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    protected function save_settings(int $user_id, array $settings): void
+    protected function save_settings(int $user_id, array $settings)
     {
         if (empty($settings))
         {
@@ -293,7 +293,7 @@ class Users_model extends EA_Model {
      * @param string $name Setting name.
      * @param string $value Setting value.
      */
-    public function set_setting(int $user_id, string $name, string $value): void
+    public function set_setting(int $user_id, string $name, string $value)
     {
         if ( ! $this->db->update('user_settings', [$name => $value], ['id_users' => $user_id]))
         {
@@ -372,7 +372,7 @@ class Users_model extends EA_Model {
      *
      * @throws InvalidArgumentException
      */
-    public function attach(array &$user, array $resources): void
+    public function attach(array &$user, array $resources)
     {
         // Users do not currently have any related resources. 
     }