diff --git a/lib/Service/SubmissionService.php b/lib/Service/SubmissionService.php
index 278fb2828..507140995 100644
--- a/lib/Service/SubmissionService.php
+++ b/lib/Service/SubmissionService.php
@@ -585,8 +585,28 @@ private function escapeCSV(string $value): string {
 		return $value;
 	}
 
+	/**
+	 * Whether the submit view shows the question to respondents: it needs a title, choice, dropdown and ranking questions need options, and grid questions need rows and columns
+	 *
+	 * @param array $question the question with its options
+	 */
+	private static function isShownToRespondents(array $question): bool {
+		if (preg_match('/^[\s\p{Z}\x{FEFF}]*$/u', (string)($question['text'] ?? '')) === 1) {
+			return false;
+		}
+
+		$optionTypes = array_map(static fn (mixed $option): mixed => is_array($option) ? ($option['optionType'] ?? null) : null, $question['options'] ?? []);
+		return match ($question['type'] ?? null) {
+			Constants::ANSWER_TYPE_MULTIPLE, Constants::ANSWER_TYPE_MULTIPLEUNIQUE, Constants::ANSWER_TYPE_DROPDOWN, Constants::ANSWER_TYPE_RANKING => $optionTypes !== [],
+			Constants::ANSWER_TYPE_GRID => in_array(Option::OPTION_TYPE_ROW, $optionTypes, true) && in_array(Option::OPTION_TYPE_COLUMN, $optionTypes, true),
+			default => true,
+		};
+	}
+
 	/**
 	 * Validate all answers against the questions
+	 * Required questions the submit view does not show to respondents need no answer
+	 *
 	 * @param array $questions Array of the questions of the form
 	 * @param array $answers Array of the submitted answers
 	 * @param string $formOwnerId Owner of the form
@@ -601,6 +621,7 @@ public function validateSubmission(array $questions, array $answers, string $for
 
 			// Check if all required questions have an answer
 			if ($question['isRequired']
+				&& self::isShownToRespondents($question)
 				&& (!$questionAnswered
 				|| !array_filter($answers[$questionId], static function (string|array $value): bool {
 					if (is_array($value)) {
@@ -674,7 +695,7 @@ public function validateSubmission(array $questions, array $answers, string $for
 					if ($question['type'] === Constants::ANSWER_TYPE_LINEARSCALE) {
 						$optionsLowest = $question['extraSettings']['optionsLowest'] ?? 1;
 						$optionsHighest = $question['extraSettings']['optionsHighest'] ?? 5;
-						if (!ctype_digit((string)$answer) || intval($answer) < $optionsLowest || intval($answer) > $optionsHighest) {
+						if (!is_scalar($answer) || is_bool($answer) || !ctype_digit((string)$answer) || intval($answer) < $optionsLowest || intval($answer) > $optionsHighest) {
 							throw new \InvalidArgumentException(sprintf('The answer for question "%s" must be an integer between %d and %d.', $question['text'], $optionsLowest, $optionsHighest));
 						}
 					}
diff --git a/tests/Unit/Service/SubmissionServiceTest.php b/tests/Unit/Service/SubmissionServiceTest.php
index e3d19a7e4..1abe556ba 100644
--- a/tests/Unit/Service/SubmissionServiceTest.php
+++ b/tests/Unit/Service/SubmissionServiceTest.php
@@ -813,6 +813,46 @@ private function setUpCsvTest(array $questions, array $submissions, string $csvT
 	// Data for validation of Submissions
 	public static function dataValidateSubmission() {
 		return [
+			'required-without-title-is-not-shown' => [
+				[
+					['id' => 1, 'type' => 'short', 'text' => '  ', 'isRequired' => true]
+				],
+				[],
+				null,
+			],
+			'required-with-unicode-space-title-is-not-shown' => [
+				[
+					['id' => 1, 'type' => 'short', 'text' => "\u{00A0}\u{3000}\u{FEFF}", 'isRequired' => true]
+				],
+				[],
+				null,
+			],
+			'required-choice-without-options-is-not-shown' => [
+				[
+					['id' => 1, 'type' => 'multiple_unique', 'text' => 'q1', 'isRequired' => true, 'options' => []]
+				],
+				[],
+				null,
+			],
+			'required-grid-without-columns-is-not-shown' => [
+				[
+					['id' => 1, 'type' => 'grid', 'text' => 'q1', 'isRequired' => true, 'options' => [
+						['id' => 3, 'optionType' => 'row']
+					]]
+				],
+				[],
+				null,
+			],
+			'required-grid-with-rows-and-columns' => [
+				[
+					['id' => 1, 'type' => 'grid', 'text' => 'q1', 'isRequired' => true, 'options' => [
+						['id' => 3, 'optionType' => 'row'],
+						['id' => 4, 'optionType' => 'column']
+					]]
+				],
+				[],
+				'Question "q1" is required.',
+			],
 			'required-not-answered' => [
 				// Questions
 				[
@@ -1185,6 +1225,24 @@ public static function dataValidateSubmission() {
 				// Expected Result
 				'The answer for question "q1" must be an integer between 0 and 5.',
 			],
+			'boolean-linearscale-answer' => [
+				[
+					['id' => 1, 'type' => 'linearscale', 'text' => 'q1', 'isRequired' => false, 'extraSettings' => ['optionsLowest' => 0]]
+				],
+				[
+					'1' => [true]
+				],
+				'The answer for question "q1" must be an integer between 0 and 5.',
+			],
+			'list-linearscale-answer' => [
+				[
+					['id' => 1, 'type' => 'linearscale', 'text' => 'q1', 'isRequired' => false, 'extraSettings' => ['optionsLowest' => 0]]
+				],
+				[
+					'1' => [['3']]
+				],
+				'The answer for question "q1" must be an integer between 0 and 5.',
+			],
 			'invalid-color-question' => [
 				// Questions
 				[