diff --git a/class-two-factor-core.php b/class-two-factor-core.php
index 7311339a..7b57b868 100644
--- a/class-two-factor-core.php
+++ b/class-two-factor-core.php
@@ -85,6 +85,13 @@ class Two_Factor_Core {
 	 */
 	private static $password_auth_tokens = array();
 
+	/**
+	 * Keep track of any errors related to setting updates.
+	 *
+	 * @var array
+	 */
+	private static $profile_errors = array();
+
 	/**
 	 * Set up filters and actions.
 	 *
@@ -114,6 +121,7 @@ public static function add_hooks( $compat ) {
 
 		// 2. Render two-factor UI after WP core has validated username/password during `wp_signon()`.
 		add_action( 'wp_login', array( __CLASS__, 'wp_login' ), PHP_INT_MAX, 2 );
+		add_action( 'user_profile_update_errors', array( __CLASS__, 'action_user_profile_update_errors' ) );
 
 		/**
 		 * Keep track of all the user sessions for which we need to invalidate the
@@ -296,7 +304,7 @@ private static function get_providers_classes( $providers ) {
 	 *
 	 * @since 0.2.0
 	 *
-	 * @return array
+	 * @return Two_Factor_Provider[]
 	 */
 	public static function get_providers() {
 		$providers = self::get_default_providers();
@@ -338,7 +346,8 @@ public static function get_providers() {
 	 * @see Two_Factor_Core::get_available_providers_for_user()
 	 *
 	 * @param  WP_User|int|null $user User ID.
-	 * @return array List of provider instances indexed by provider key.
+	 *
+	 * @return Two_Factor_Provider[] List of provider instances indexed by provider key.
 	 */
 	public static function get_supported_providers_for_user( $user = null ) {
 		$user      = self::fetch_user( $user );
@@ -403,6 +412,36 @@ public static function add_settings_action_link( $links ) {
 		return $links;
 	}
 
+	/**
+	 * Register an error associated with the current request.
+	 *
+	 * @param WP_Error $error Error instance.
+
+	 * @return void
+	 */
+	private static function add_error( WP_Error $error ) {
+		self::$profile_errors[ $error->get_error_code() ] = $error;
+	}
+
+	/**
+	 * Attach Two-Factor profile errors to WordPress core profile update errors.
+	 *
+	 * @since NEXT
+	 *
+	 * @param WP_Error $errors WP_Error object passed by core.
+	 *
+	 * @return void
+	 */
+	public static function action_user_profile_update_errors( WP_Error $errors ) {
+		foreach ( self::$profile_errors as $profile_error ) {
+			foreach ( $profile_error->get_error_codes() as $code ) {
+				foreach ( $profile_error->get_error_messages( $code ) as $message ) {
+					$errors->add( $code, $message );
+				}
+			}
+		}
+	}
+
 	/**
 	 * Check if the debug mode is enabled.
 	 *
@@ -599,7 +638,8 @@ public static function fetch_user( $user = null ) {
 	 * @see Two_Factor_Core::get_available_providers_for_user()
 	 *
 	 * @param int|WP_User $user Optional. User ID, or WP_User object of the the user. Defaults to current user.
-	 * @return array
+	 *
+	 * @return string[] List of keys of enabled providers for the user.
 	 */
 	public static function get_enabled_providers_for_user( $user = null ) {
 		$user = self::fetch_user( $user );
@@ -635,7 +675,7 @@ public static function get_enabled_providers_for_user( $user = null ) {
 	 * @see Two_Factor_Core::get_enabled_providers_for_user()
 	 *
 	 * @param int|WP_User $user Optional. User ID, or WP_User object of the the user. Defaults to current user.
-	 * @return array|WP_Error List of provider instances, or a WP_Error if all configured providers are unavailable.
+	 * @return Two_Factor_Provider[]|WP_Error List of provider instances, or a WP_Error if all configured providers are unavailable.
 	 */
 	public static function get_available_providers_for_user( $user = null ) {
 		$user = self::fetch_user( $user );
@@ -2044,8 +2084,6 @@ public static function manage_users_custom_column( $output, $column_name, $user_
 	 * @param WP_User $user WP_User object of the logged-in user.
 	 */
 	public static function user_two_factor_options( $user ) {
-		$notices = array();
-
 		$providers = self::get_supported_providers_for_user( $user );
 
 		wp_enqueue_style( 'user-edit-2fa', plugins_url( 'user-edit.css', __FILE__ ), array(), TWO_FACTOR_VERSION );
@@ -2062,29 +2100,58 @@ public static function user_two_factor_options( $user ) {
 				self::get_user_two_factor_revalidate_url()
 			);
 
-			$notices['warning two-factor-warning-revalidate-session'] = sprintf(
-				/* translators: %s: URL to revalidate the session */
-				__( 'To update your Two-Factor options, you must first revalidate your session. <a class="button" href="%s">Revalidate now</a>', 'two-factor' ),
-				esc_url( $url )
+			self::add_error(
+				new WP_Error(
+					'two_factor_revalidate_session',
+					sprintf(
+						__( 'To update your Two-Factor options, you must first revalidate your session.', 'two-factor' ) .
+						' <a class="button" href="%s">' . esc_html__( 'Revalidate now', 'two-factor' ) . '</a>',
+						esc_url( $url )
+					),
+					array(
+						'type' => 'warning',
+					)
+				)
 			);
 		}
 
 		if ( empty( $providers ) ) {
-			$notices['notice two-factor-notice-no-providers-supported'] = esc_html__( 'No providers are available for your account.', 'two-factor' );
+			self::add_error(
+				new WP_Error(
+					'two_factor_no_providers_supported',
+					__( 'No providers are available for your account.', 'two-factor' ),
+					array(
+						'type' => 'notice',
+					)
+				)
+			);
 		}
 
 		// Suggest enabling a backup method if only one method is enabled and there are more available.
 		if ( count( $providers ) > 1 && 1 === count( $enabled_providers ) ) {
-			$notices['warning two-factor-warning-suggest-backup'] = esc_html__( 'To prevent being locked out of your account, consider enabling a backup method like Recovery Codes in case you lose access to your primary authentication method.', 'two-factor' );
+			self::add_error(
+				new WP_Error(
+					'two_factor_suggest_backup',
+					__( 'To prevent being locked out of your account, consider enabling a backup method like Recovery Codes in case you lose access to your primary authentication method.', 'two-factor' ),
+					array(
+						'type' => 'warning',
+					)
+				)
+			);
 		}
+
+		$generic_errors = array_filter(
+			self::$profile_errors,
+			static function ( WP_Error $error ) {
+				$error_data = $error->get_error_data();
+				return empty( $error_data['provider'] ); // Where the associated provider is not set.
+			}
+		);
+
 		?>
 		<h2><?php esc_html_e( 'Two-Factor Options', 'two-factor' ); ?></h2>
 
-		<?php foreach ( $notices as $notice_type => $notice ) : ?>
-		<div class="<?php echo esc_attr( $notice_type ? 'notice inline notice-' . $notice_type : '' ); ?>">
-			<p><?php echo wp_kses_post( $notice ); ?></p>
-		</div>
-		<?php endforeach; ?>
+		<?php self::render_errors( $generic_errors ); ?>
 
 		<fieldset id="two-factor-options" <?php echo $show_2fa_options ? '' : 'disabled="disabled"'; ?>>
 		<legend class="screen-reader-text"><?php esc_html_e( 'Two-Factor Options', 'two-factor' ); ?></legend>
@@ -2135,6 +2202,27 @@ private static function get_recommended_providers( $user ) {
 		return (array) apply_filters( 'two_factor_recommended_providers', $providers, $user );
 	}
 
+	/**
+	 * Render WP errors.
+	 *
+	 * @param WP_Error[] $errors List of errors to render.
+	 */
+	private static function render_errors( array $errors ) {
+		foreach ( $errors as $error ) {
+			if ( $error->has_errors() ) {
+				$error_type = $error->get_error_data()['type'] ?? null;
+
+				wp_admin_notice(
+					implode( '</p><p>', $error->get_error_messages() ),
+					array(
+						'type'               => is_string( $error_type ) ? $error_type : 'error',
+						'additional_classes' => array( 'inline' ),
+					)
+				);
+			}
+		}
+	}
+
 	/**
 	 * Render the user settings.
 	 *
@@ -2145,7 +2233,7 @@ private static function get_recommended_providers( $user ) {
 	 */
 	private static function render_user_providers_form( $user, $providers ) {
 		$primary_provider_key      = self::get_primary_provider_key_selected_for_user( $user );
-		$enabled_providers         = self::get_enabled_providers_for_user( $user );
+		$available_providers       = self::get_available_providers_for_user( $user );
 		$recommended_provider_keys = self::get_recommended_providers( $user );
 
 		// Move the recommended providers first.
@@ -2172,8 +2260,9 @@ private static function render_user_providers_form( $user, $providers ) {
 				<tr>
 					<th><?php echo esc_html( $object->get_label() ); ?></th>
 					<td>
+						<?php self::render_errors( self::get_provider_errors( $provider_key ) ); ?>
 						<label class="two-factor-method-label">
-							<input id="enabled-<?php echo esc_attr( $provider_key ); ?>" type="checkbox" name="<?php echo esc_attr( self::ENABLED_PROVIDERS_USER_META_KEY ); ?>[]" value="<?php echo esc_attr( $provider_key ); ?>" <?php checked( in_array( $provider_key, $enabled_providers, true ) ); ?> />
+							<input id="enabled-<?php echo esc_attr( $provider_key ); ?>" type="checkbox" name="<?php echo esc_attr( self::ENABLED_PROVIDERS_USER_META_KEY ); ?>[]" value="<?php echo esc_attr( $provider_key ); ?>" <?php checked( isset( $available_providers[ $provider_key ] ) ); ?> />
 							<?php /* translators: %s: authentication method name. */ ?>
 							<strong><?php echo esc_html( sprintf( __( 'Enable %s', 'two-factor' ), $object->get_label() ) ); ?></strong>
 							<?php if ( in_array( $provider_key, $recommended_provider_keys, true ) ) : ?>
@@ -2207,7 +2296,7 @@ private static function render_user_providers_form( $user, $providers ) {
 						<select id="two-factor-primary-provider" name="<?php echo esc_attr( self::PROVIDER_USER_META_KEY ); ?>">
 							<option value=""><?php echo esc_html( __( 'Default', 'two-factor' ) ); ?></option>
 							<?php foreach ( $providers as $provider_key => $object ) : ?>
-								<option value="<?php echo esc_attr( $provider_key ); ?>" <?php selected( $provider_key, $primary_provider_key ); ?> <?php disabled( ! in_array( $provider_key, $enabled_providers, true ) ); ?>>
+								<option value="<?php echo esc_attr( $provider_key ); ?>" <?php selected( $provider_key, $primary_provider_key ); ?> <?php disabled( ! isset( $available_providers[ $provider_key ] ) ); ?>>
 									<?php echo esc_html( $object->get_label() ); ?>
 								</option>
 							<?php endforeach; ?>
@@ -2220,6 +2309,24 @@ private static function render_user_providers_form( $user, $providers ) {
 		<?php
 	}
 
+	/**
+	 * Get the errors marked for a specific provider.
+	 *
+	 * @param string $provider_key The provider key to get errors for.
+	 *
+	 * @return WP_Error[] List of errors for the provider.
+	 */
+	private static function get_provider_errors( string $provider_key ): array {
+		return array_filter(
+			self::$profile_errors,
+			static function ( WP_Error $error ) use ( $provider_key ) {
+				$error_data = $error->get_error_data(); // Return the data for the first error.
+
+				return isset( $error_data['provider'] ) && $error_data['provider'] === $provider_key;
+			}
+		);
+	}
+
 	/**
 	 * Enable a provider for a user.
 	 *
@@ -2311,17 +2418,40 @@ public static function user_two_factor_options_update( $user_id ) {
 				return;
 			}
 
+			$user               = self::fetch_user( $user_id );
 			$providers          = self::get_supported_providers_for_user( $user_id );
 			$enabled_providers  = $_POST[ self::ENABLED_PROVIDERS_USER_META_KEY ];
 			$existing_providers = self::get_enabled_providers_for_user( $user_id );
 
 			// Enable only the available providers.
-			$enabled_providers = array_intersect( $enabled_providers, array_keys( $providers ) );
-			update_user_meta( $user_id, self::ENABLED_PROVIDERS_USER_META_KEY, $enabled_providers );
+			$enabled_providers = array_intersect_key( $providers, array_flip( $enabled_providers ) );
+
+			// Ensure the enabled providers are configured and can be enabled.
+			foreach ( $enabled_providers as $provider_key => $provider ) {
+				if ( ! $provider->is_available_for_user( $user ) ) {
+					unset( $enabled_providers[ $provider_key ] );
+
+					self::add_error(
+						new WP_Error(
+							'two_factor_provider_not_configured_' . $provider_key,
+							sprintf(
+								/* translators: %s: provider label. */
+								__( 'The %s method must be configured before it can be enabled.', 'two-factor' ),
+								esc_html( $provider->get_label() )
+							),
+							array(
+								'provider' => $provider_key,
+							)
+						)
+					);
+				}
+			}
+
+			update_user_meta( $user_id, self::ENABLED_PROVIDERS_USER_META_KEY, array_keys( $enabled_providers ) );
 
 			// Primary provider must be enabled.
 			$new_provider = isset( $_POST[ self::PROVIDER_USER_META_KEY ] ) ? $_POST[ self::PROVIDER_USER_META_KEY ] : '';
-			if ( ! empty( $new_provider ) && in_array( $new_provider, $enabled_providers, true ) ) {
+			if ( ! empty( $new_provider ) && isset( $enabled_providers[ $new_provider ] ) ) {
 				update_user_meta( $user_id, self::PROVIDER_USER_META_KEY, $new_provider );
 			} else {
 				delete_user_meta( $user_id, self::PROVIDER_USER_META_KEY );
@@ -2354,7 +2484,7 @@ public static function user_two_factor_options_update( $user_id ) {
 				// No providers, enabling one (or more)
 				( ! $existing_providers && $enabled_providers ) ||
 				// Has providers, and is disabling one (or more), but remaining with 2FA.
-				( $existing_providers && $enabled_providers && array_diff( $existing_providers, $enabled_providers ) )
+				( $existing_providers && $enabled_providers && array_diff( $existing_providers, array_keys( $enabled_providers ) ) )
 			) {
 				if ( $user_id === get_current_user_id() ) {
 					// Keep the current session, destroy others sessions for this user.