diff --git a/approot/settings.xml b/approot/settings.xml
index 83585400..a095b403 100644
--- a/approot/settings.xml
+++ b/approot/settings.xml
@@ -55,9 +55,9 @@
 			<div class="input-group mb-3">
 				${replaygain-preamp class="form-control"}
 				<span class="input-group-text">dB</span>
-			</div>
-			<div class="invalid-feedback">
-				${replaygain-preamp-info}
+				<div class="invalid-feedback">
+					${replaygain-preamp-info}
+				</div>
 			</div>
 		</div>
 		<div class="col-lg-4">
@@ -67,9 +67,9 @@
 			<div class="input-group mb-3">
 				${replaygain-preamp-no-rg-info class="form-control"}
 				<span class="input-group-text">dB</span>
-			</div>
-			<div class="invalid-feedback">
-				${replaygain-preamp-no-rg-info-info}
+				<div class="invalid-feedback">
+					${replaygain-preamp-no-rg-info-info}
+				</div>
 			</div>
 		</div>
 		${<if-has-subsonic-api>}
diff --git a/src/lms/CMakeLists.txt b/src/lms/CMakeLists.txt
index 3b01a5c6..8e922082 100644
--- a/src/lms/CMakeLists.txt
+++ b/src/lms/CMakeLists.txt
@@ -18,6 +18,7 @@ add_executable(lms
 	ui/admin/UserView.cpp
 	ui/admin/UsersView.cpp
 	ui/common/DirectoryValidator.cpp
+	ui/common/DoubleValidator.cpp
 	ui/common/InfiniteScrollingContainer.cpp
 	ui/common/LoadingIndicator.cpp
 	ui/common/LoginNameValidator.cpp
diff --git a/src/lms/ui/SettingsView.cpp b/src/lms/ui/SettingsView.cpp
index 9b68c141..66aaad6b 100644
--- a/src/lms/ui/SettingsView.cpp
+++ b/src/lms/ui/SettingsView.cpp
@@ -21,7 +21,6 @@
 
 #include <Wt/WCheckBox.h>
 #include <Wt/WComboBox.h>
-#include <Wt/WDoubleValidator.h>
 #include <Wt/WDoubleSpinBox.h>
 #include <Wt/WFormModel.h>
 #include <Wt/WLineEdit.h>
@@ -29,8 +28,9 @@
 #include <Wt/WString.h>
 #include <Wt/WTemplateFormView.h>
 
-#include "common/PasswordValidator.hpp"
+#include "common/DoubleValidator.hpp"
 #include "common/MandatoryValidator.hpp"
+#include "common/PasswordValidator.hpp"
 #include "common/UUIDValidator.hpp"
 #include "common/ValueStringModel.hpp"
 
@@ -108,12 +108,10 @@ class SettingsModel : public Wt::WFormModel
 			setValidator(TranscodeBitrateField, createMandatoryValidator());
 			setValidator(TranscodeFormatField, createMandatoryValidator());
 			setValidator(ReplayGainModeField, createMandatoryValidator());
-			auto createPreAmpValidator = []
+			auto createPreAmpValidator {[]
 			{
-				auto preampGainValidator {std::make_unique<Wt::WDoubleValidator>()};
-				preampGainValidator->setRange(MediaPlayer::Settings::ReplayGain::minPreAmpGain, MediaPlayer::Settings::ReplayGain::maxPreAmpGain);
-				return preampGainValidator;
-			};
+				return createDoubleValidator(MediaPlayer::Settings::ReplayGain::minPreAmpGain, MediaPlayer::Settings::ReplayGain::maxPreAmpGain);
+			}};
 
 			setValidator(ReplayGainPreAmpGainField, createPreAmpValidator());
 			setValidator(ReplayGainPreAmpGainIfNoInfoField, createPreAmpValidator());
diff --git a/src/lms/ui/admin/DatabaseSettingsView.cpp b/src/lms/ui/admin/DatabaseSettingsView.cpp
index 9a145c07..ee291749 100644
--- a/src/lms/ui/admin/DatabaseSettingsView.cpp
+++ b/src/lms/ui/admin/DatabaseSettingsView.cpp
@@ -69,12 +69,11 @@ class DatabaseSettingsModel : public Wt::WFormModel
 
 			auto dirValidator {createDirectoryValidator()};
 			dirValidator->setMandatory(true);
-			setValidator(MediaDirectoryField, dirValidator);
+			setValidator(MediaDirectoryField, move(dirValidator));
 
 			setValidator(UpdatePeriodField, createMandatoryValidator());
 			setValidator(UpdateStartTimeField, createMandatoryValidator());
 			setValidator(RecommendationEngineTypeField, createMandatoryValidator());
-			setValidator(TagsField, createTagsValidator());
 
 			// populate the model with initial data
 			loadData();
@@ -144,11 +143,6 @@ class DatabaseSettingsModel : public Wt::WFormModel
 		}
 
 	private:
-		static std::shared_ptr<Wt::WValidator> createTagsValidator()
-		{
-			auto v = std::make_shared<Wt::WValidator>();
-			return v;
-		}
 
 		void initializeModels()
 		{
diff --git a/src/lms/ui/common/DirectoryValidator.cpp b/src/lms/ui/common/DirectoryValidator.cpp
index b55fe38e..f79d57cb 100644
--- a/src/lms/ui/common/DirectoryValidator.cpp
+++ b/src/lms/ui/common/DirectoryValidator.cpp
@@ -25,8 +25,9 @@ namespace UserInterface
 {
 	class DirectoryValidator : public Wt::WValidator
 	{
-		public:
+		private:
 			Wt::WValidator::Result validate(const Wt::WString& input) const override;
+			std::string javaScriptValidate() const override { return {}; }
 	};
 
 	Wt::WValidator::Result
@@ -48,7 +49,7 @@ namespace UserInterface
 			return Wt::WValidator::Result(Wt::ValidationState::Invalid, Wt::WString::tr("Lms.not-a-directory"));
 	}
 
-	std::shared_ptr<Wt::WValidator>
+	std::unique_ptr<Wt::WValidator>
 	createDirectoryValidator()
 	{
 		return std::make_unique<DirectoryValidator>();
diff --git a/src/lms/ui/common/DirectoryValidator.hpp b/src/lms/ui/common/DirectoryValidator.hpp
index 08cc26aa..8acec345 100644
--- a/src/lms/ui/common/DirectoryValidator.hpp
+++ b/src/lms/ui/common/DirectoryValidator.hpp
@@ -23,6 +23,6 @@
 
 namespace UserInterface
 {
-	std::shared_ptr<Wt::WValidator> createDirectoryValidator();
+	std::unique_ptr<Wt::WValidator> createDirectoryValidator();
 } // namespace UserInterface
 
diff --git a/src/lms/ui/common/DoubleValidator.cpp b/src/lms/ui/common/DoubleValidator.cpp
new file mode 100644
index 00000000..89f47220
--- /dev/null
+++ b/src/lms/ui/common/DoubleValidator.cpp
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2022 Emeric Poupon
+ *
+ * This file is part of LMS.
+ *
+ * LMS is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * LMS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with LMS.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "DoubleValidator.hpp"
+
+#include <Wt/WDoubleValidator.h>
+
+namespace UserInterface
+{
+	class DoubleValidator : public Wt::WDoubleValidator
+	{
+		public:
+			using Wt::WDoubleValidator::WDoubleValidator;
+
+		private:
+			std::string javaScriptValidate() const override { return {}; }
+	};
+
+	std::unique_ptr<Wt::WValidator>
+	createDoubleValidator(double min, double max)
+	{
+		auto validator {std::make_unique<DoubleValidator>(min, max)};
+		return validator;
+	}
+} // namespace UserInterface
diff --git a/src/lms/ui/common/DoubleValidator.hpp b/src/lms/ui/common/DoubleValidator.hpp
new file mode 100644
index 00000000..b1da20ab
--- /dev/null
+++ b/src/lms/ui/common/DoubleValidator.hpp
@@ -0,0 +1,28 @@
+/*
+ * Copyright (C) 2022 Emeric Poupon
+ *
+ * This file is part of LMS.
+ *
+ * LMS is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * LMS is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with LMS.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <Wt/WValidator.h>
+
+namespace UserInterface
+{
+	std::unique_ptr<Wt::WValidator> createDoubleValidator(double min, double max);
+} // namespace UserInterface
+
diff --git a/src/lms/ui/common/LoginNameValidator.cpp b/src/lms/ui/common/LoginNameValidator.cpp
index 5fc121cf..78bacc60 100644
--- a/src/lms/ui/common/LoginNameValidator.cpp
+++ b/src/lms/ui/common/LoginNameValidator.cpp
@@ -24,10 +24,16 @@
 
 namespace UserInterface
 {
-	std::shared_ptr<Wt::WValidator>
+	class LengthValidator : public Wt::WLengthValidator
+	{
+		private:
+			std::string javaScriptValidate() const override { return {}; }
+	};
+
+	std::unique_ptr<Wt::WValidator>
 	createLoginNameValidator()
 	{
-		auto v = std::make_unique<Wt::WLengthValidator>();
+		auto v = std::make_unique<LengthValidator>();
 		v->setMandatory(true);
 		v->setMinimumLength(::Database::User::MinNameLength);
 		v->setMaximumLength(::Database::User::MaxNameLength);
diff --git a/src/lms/ui/common/LoginNameValidator.hpp b/src/lms/ui/common/LoginNameValidator.hpp
index b67c92d5..d4436dae 100644
--- a/src/lms/ui/common/LoginNameValidator.hpp
+++ b/src/lms/ui/common/LoginNameValidator.hpp
@@ -23,6 +23,6 @@
 
 namespace UserInterface
 {
-	std::shared_ptr<Wt::WValidator> createLoginNameValidator();
+	std::unique_ptr<Wt::WValidator> createLoginNameValidator();
 } // namespace UserInterface
 
diff --git a/src/lms/ui/common/MandatoryValidator.cpp b/src/lms/ui/common/MandatoryValidator.cpp
index ca60f369..a5cb1caf 100644
--- a/src/lms/ui/common/MandatoryValidator.cpp
+++ b/src/lms/ui/common/MandatoryValidator.cpp
@@ -21,10 +21,16 @@
 
 namespace UserInterface
 {
-	std::shared_ptr<Wt::WValidator>
+	class MandatoryValidator : public Wt::WValidator
+	{
+		private:
+			std::string javaScriptValidate() const override { return {}; }
+	};
+
+	std::unique_ptr<Wt::WValidator>
 	createMandatoryValidator()
 	{
-		auto v {std::make_shared<Wt::WValidator>()};
+		auto v {std::make_unique<MandatoryValidator>()};
 		v->setMandatory(true);
 		return v;
 	}
diff --git a/src/lms/ui/common/MandatoryValidator.hpp b/src/lms/ui/common/MandatoryValidator.hpp
index 6fac9a04..ed074336 100644
--- a/src/lms/ui/common/MandatoryValidator.hpp
+++ b/src/lms/ui/common/MandatoryValidator.hpp
@@ -23,6 +23,6 @@
 
 namespace UserInterface
 {
-	std::shared_ptr<Wt::WValidator> createMandatoryValidator();
+	std::unique_ptr<Wt::WValidator> createMandatoryValidator();
 } // namespace UserInterface
 
diff --git a/src/lms/ui/common/PasswordValidator.cpp b/src/lms/ui/common/PasswordValidator.cpp
index 2979739e..7160c40d 100644
--- a/src/lms/ui/common/PasswordValidator.cpp
+++ b/src/lms/ui/common/PasswordValidator.cpp
@@ -36,6 +36,7 @@ namespace UserInterface
 
 		private:
 			Wt::WValidator::Result validate(const Wt::WString& input) const override;
+			std::string javaScriptValidate() const override { return {}; }
 
 			PasswordValidationContextGetFunc _passwordValidationContextGetFunc;
 	};
@@ -61,16 +62,17 @@ namespace UserInterface
 		throw LmsException {"internal error"};
 	}
 
-	std::shared_ptr<Wt::WValidator>
+	std::unique_ptr<Wt::WValidator>
 	createPasswordStrengthValidator(PasswordValidationContextGetFunc passwordValidationContextGetFunc)
 	{
-		return std::make_shared<PasswordStrengthValidator>(std::move(passwordValidationContextGetFunc));
+		return std::make_unique<PasswordStrengthValidator>(std::move(passwordValidationContextGetFunc));
 	}
 
 	class PasswordCheckValidator : public Wt::WValidator
 	{
-		public:
+		private:
 			Wt::WValidator::Result validate(const Wt::WString& input) const override;
+			std::string javaScriptValidate() const override { return {}; }
 	};
 
 	Wt::WValidator::Result
@@ -96,10 +98,10 @@ namespace UserInterface
 		throw LmsException {"InternalError"};
 	}
 
-	std::shared_ptr<Wt::WValidator>
+	std::unique_ptr<Wt::WValidator>
 	createPasswordCheckValidator()
 	{
-		return std::make_shared<PasswordCheckValidator>();
+		return std::make_unique<PasswordCheckValidator>();
 	}
 
 } // namespace UserInterface
diff --git a/src/lms/ui/common/PasswordValidator.hpp b/src/lms/ui/common/PasswordValidator.hpp
index e3b5a708..aba53bb8 100644
--- a/src/lms/ui/common/PasswordValidator.hpp
+++ b/src/lms/ui/common/PasswordValidator.hpp
@@ -22,15 +22,14 @@
 #include <functional>
 #include <Wt/WValidator.h>
 
-#include "services/database/Types.hpp"
 #include "services/auth/Types.hpp"
 
 namespace UserInterface
 {
 	using PasswordValidationContextGetFunc = std::function<::Auth::PasswordValidationContext()>;
-	std::shared_ptr<Wt::WValidator> createPasswordStrengthValidator(PasswordValidationContextGetFunc passwordValidationContextGetFunc);
+	std::unique_ptr<Wt::WValidator> createPasswordStrengthValidator(PasswordValidationContextGetFunc passwordValidationContextGetFunc);
 
 	// Check current user password
-	std::shared_ptr<Wt::WValidator> createPasswordCheckValidator();
+	std::unique_ptr<Wt::WValidator> createPasswordCheckValidator();
 } // namespace UserInterface
 
diff --git a/src/lms/ui/common/UUIDValidator.cpp b/src/lms/ui/common/UUIDValidator.cpp
index a333c7be..3399ae82 100644
--- a/src/lms/ui/common/UUIDValidator.cpp
+++ b/src/lms/ui/common/UUIDValidator.cpp
@@ -23,9 +23,18 @@
 
 namespace UserInterface
 {
-	std::shared_ptr<Wt::WValidator>
+	class RegExpValidator : public Wt::WRegExpValidator
+	{
+		public:
+			using Wt::WRegExpValidator::WRegExpValidator;
+
+		private:
+			std::string javaScriptValidate() const override { return {}; }
+	};
+
+	std::unique_ptr<Wt::WValidator>
 	createUUIDValidator()
 	{
-		return std::make_unique<Wt::WRegExpValidator>("[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}");
+		return std::make_unique<RegExpValidator>("[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{4}-[a-fA-F0-9]{12}");
 	}
 } // namespace UserInterface
diff --git a/src/lms/ui/common/UUIDValidator.hpp b/src/lms/ui/common/UUIDValidator.hpp
index e6120e5d..9593b08a 100644
--- a/src/lms/ui/common/UUIDValidator.hpp
+++ b/src/lms/ui/common/UUIDValidator.hpp
@@ -23,6 +23,6 @@
 
 namespace UserInterface
 {
-	std::shared_ptr<Wt::WValidator> createUUIDValidator();
+	std::unique_ptr<Wt::WValidator> createUUIDValidator();
 } // namespace UserInterface