diff --git a/lib/Controller/ApiController.php b/lib/Controller/ApiController.php
index 848155601..096cf5e45 100644
--- a/lib/Controller/ApiController.php
+++ b/lib/Controller/ApiController.php
@@ -894,7 +894,7 @@ public function reorderQuestions(int $formId, array $newOrder): DataResponse {
 	 * @param int $formId id of the form
 	 * @param int $questionId id of the question
 	 * @param list<string> $optionTexts the new option text
-	 * @param string|null $optionType the new option type (e.g. 'row')
+	 * @param string|null $optionType the new option type (e.g. 'row'), defaults to 'choice'
 	 * @return DataResponse<Http::STATUS_CREATED, list<FormsOption>, array{}> Returns a DataResponse containing the added options
 	 * @throws OCSBadRequestException This question is not part ot the given form
 	 * @throws OCSForbiddenException This form is archived and can not be modified
@@ -908,7 +908,7 @@ public function reorderQuestions(int $formId, array $newOrder): DataResponse {
 	#[NoAdminRequired()]
 	#[BruteForceProtection(action: 'form')]
 	#[ApiRoute(verb: 'POST', url: '/api/v3/forms/{formId}/questions/{questionId}/options')]
-	public function newOption(int $formId, int $questionId, array $optionTexts, ?string $optionType = null): DataResponse {
+	public function newOption(int $formId, int $questionId, array $optionTexts, ?string $optionType = 'choice'): DataResponse {
 		$this->logger->debug('Adding new options: formId: {formId}, questionId: {questionId}, text: {text}, optionType: {optionType}', [
 			'formId' => $formId,
 			'questionId' => $questionId,
diff --git a/lib/Migration/Version050300Date20260716000000.php b/lib/Migration/Version050300Date20260716000000.php
new file mode 100644
index 000000000..c5becf402
--- /dev/null
+++ b/lib/Migration/Version050300Date20260716000000.php
@@ -0,0 +1,67 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Forms\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\IDBConnection;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+
+/**
+ * Gives the option_type column a 'choice' default and backfills existing
+ * rows that were stored without a type. Options created through the API
+ * without an explicit optionType previously kept a null type, which the
+ * frontend does not render.
+ */
+class Version050300Date20260716000000 extends SimpleMigrationStep {
+
+	public function __construct(
+		protected IDBConnection $db,
+	) {
+	}
+
+	/**
+	 * @param IOutput $output
+	 * @param Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
+	 * @param array $options
+	 * @return null|ISchemaWrapper
+	 */
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		/** @var ISchemaWrapper $schema */
+		$schema = $schemaClosure();
+		$table = $schema->getTable('forms_v2_options');
+		$changed = false;
+
+		if ($table->hasColumn('option_type')) {
+			$column = $table->getColumn('option_type');
+			if ($column->getDefault() === null) {
+				$column->setDefault('choice');
+				$changed = true;
+			}
+		}
+
+		return $changed ? $schema : null;
+	}
+
+	/**
+	 * @param IOutput $output
+	 * @param Closure(): ISchemaWrapper $schemaClosure
+	 * @param array $options
+	 */
+	public function postSchemaChange(IOutput $output, Closure $schemaClosure, array $options): void {
+		$qbUpdate = $this->db->getQueryBuilder();
+
+		$qbUpdate->update('forms_v2_options')
+			->set('option_type', $qbUpdate->createNamedParameter('choice'))
+			->where($qbUpdate->expr()->isNull('option_type'))
+			->executeStatement();
+	}
+}
diff --git a/openapi.json b/openapi.json
index 5bedb6c5d..f9eb1da32 100644
--- a/openapi.json
+++ b/openapi.json
@@ -2702,8 +2702,8 @@
                                     "optionType": {
                                         "type": "string",
                                         "nullable": true,
-                                        "default": null,
-                                        "description": "the new option type (e.g. 'row')"
+                                        "default": "choice",
+                                        "description": "the new option type (e.g. 'row'), defaults to 'choice'"
                                     }
                                 }
                             }
diff --git a/tests/Integration/Api/ApiV3Test.php b/tests/Integration/Api/ApiV3Test.php
index a4f4328d2..e869016b2 100644
--- a/tests/Integration/Api/ApiV3Test.php
+++ b/tests/Integration/Api/ApiV3Test.php
@@ -497,17 +497,17 @@ public static function dataGetFullForm() {
 								[
 									'text' => 'Option 1',
 									'order' => 1,
-									'optionType' => null,
+									'optionType' => 'choice',
 								],
 								[
 									'text' => 'Option 2',
 									'order' => 2,
-									'optionType' => null,
+									'optionType' => 'choice',
 								],
 								[
 									'text' => '',
 									'order' => 3,
-									'optionType' => null,
+									'optionType' => 'choice',
 								]
 							],
 							'accept' => [],
@@ -1027,7 +1027,9 @@ public static function dataCreateNewOption() {
 					// 'questionId' => Done dynamically below.
 					'text' => 'A new Option.',
 					'order' => 4,
-					'optionType' => null,
+					// Non-grid questions default to the 'choice' option type
+					// when none is provided.
+					'optionType' => 'choice',
 				]
 			]
 		];