diff --git a/plugins/faustwp/includes/settings/callbacks.php b/plugins/faustwp/includes/settings/callbacks.php
index 91a0d73f2..4a81aca67 100644
--- a/plugins/faustwp/includes/settings/callbacks.php
+++ b/plugins/faustwp/includes/settings/callbacks.php
@@ -203,7 +203,7 @@ function sanitize_faustwp_settings( $settings, $option ) {
 
 		switch ( $name ) {
 			case 'frontend_uri':
-				if ( '' === $value || preg_match( '#http(s?)://(.+)#i', $value ) ) {
+				if ( '' === $value || ( is_string( $value ) && preg_match( '#http(s?)://(.+)#i', $value ) ) ) {
 					$settings[ $name ] = esc_url_raw( $value, $protocols );
 				} else {
 					$errors[ $name ]   = __( 'The Front-end site URL you entered did not appear to be a valid URL. Please enter a valid URL.', 'faustwp' );
@@ -566,5 +566,6 @@ function trim_frontend_uri_trailing_slash( $value, $name ) {
 		return $value;
 	}
 
-	return untrailingslashit( $value );
+	// A front-end URL saved outside the settings screen may be null.
+	return untrailingslashit( (string) $value );
 }
diff --git a/plugins/faustwp/phpunit.xml.dist b/plugins/faustwp/phpunit.xml.dist
index 14b76e3d9..b4107a0b1 100644
--- a/plugins/faustwp/phpunit.xml.dist
+++ b/plugins/faustwp/phpunit.xml.dist
@@ -3,6 +3,7 @@
   backupGlobals="false"
   bootstrap="tests/bootstrap.php"
   colors="true"
+  convertDeprecationsToExceptions="true"
   convertErrorsToExceptions="true"
   convertNoticesToExceptions="true"
   convertWarningsToExceptions="true"
diff --git a/plugins/faustwp/tests/integration/ProcessTelemetryRouteTests.php b/plugins/faustwp/tests/integration/ProcessTelemetryRouteTests.php
index e2d720d0b..dc4809b70 100644
--- a/plugins/faustwp/tests/integration/ProcessTelemetryRouteTests.php
+++ b/plugins/faustwp/tests/integration/ProcessTelemetryRouteTests.php
@@ -7,6 +7,7 @@
 
 class ProcessTelemetryRouteTests extends WP_UnitTestCase
 {
+  private $server;
   private $request;
   private $route_name;
 
diff --git a/plugins/faustwp/tests/integration/SettingsCallbacksTests.php b/plugins/faustwp/tests/integration/SettingsCallbacksTests.php
index d09238080..663a12adb 100644
--- a/plugins/faustwp/tests/integration/SettingsCallbacksTests.php
+++ b/plugins/faustwp/tests/integration/SettingsCallbacksTests.php
@@ -8,6 +8,7 @@
 namespace WPE\FaustWP\Tests\Integration;
 
 use function WPE\FaustWP\Settings\sanitize_faustwp_settings;
+use function WPE\FaustWP\Settings\trim_frontend_uri_trailing_slash;
 
 class SettingsCallbacksTests extends \WP_UnitTestCase {
 
@@ -41,6 +42,20 @@ public function test_sanitize_faustwp_settings_does_not_change_existing_settings
 		$this->assertSame( $this->init_settings, sanitize_faustwp_settings( $this->init_settings, $this->option ) );
 	}
 
+	public function test_sanitize_faustwp_settings_rejects_a_null_frontend_uri() {
+		$sanitized = sanitize_faustwp_settings( [ 'frontend_uri' => null ], $this->option );
+
+		$this->assertSame( $this->init_settings['frontend_uri'], $sanitized['frontend_uri'] );
+		$errors = get_settings_errors( $this->option );
+		$this->assertCount( 1, $errors );
+		$this->assertEquals( $errors[0]['code'], 'faustwp_invalid_frontend_uri' );
+	}
+
+	public function test_trim_frontend_uri_trailing_slash_handles_a_null_frontend_uri() {
+		$this->assertSame( '', trim_frontend_uri_trailing_slash( null, 'frontend_uri' ) );
+		$this->assertSame( 'http://localhost:3000', trim_frontend_uri_trailing_slash( 'http://localhost:3000/', 'frontend_uri' ) );
+	}
+
 	public function test_sanitize_faustwp_settings_allows_valid_frontend_uris() {
 		$valid_uris = [
 			// Clean URLs