diff --git a/src/Application/Api/Services/Api.php b/src/Application/Api/Services/Api.php
index 615f619e0..111ae84ef 100644
--- a/src/Application/Api/Services/Api.php
+++ b/src/Application/Api/Services/Api.php
@@ -415,7 +415,14 @@ public function getParamArray(string $param, bool $required = false, $default =
         $value = $this->getParam($param, $required, $default);
 
         if (null !== $value) {
-            if (!is_array($value)) {
+            // The elements as well as the container. Checking only `is_array()` let `[true]` or
+            // `[[1]]` through to `Filter::getArray()`, which threw a `TypeError` — the 500 with a
+            // class name and a server path in the body that the three scalar readers above were
+            // already fixed to refuse with a 400. An element is an id or a value, so the same
+            // scalars those readers accept are the ones accepted here.
+            if (!is_array($value)
+                || array_filter($value, static fn($item) => !is_int($item) && !is_string($item) && $item !== null)
+            ) {
                 throw $this->wrongParameterType();
             }
 
diff --git a/src/Domain/Common/Providers/Filter.php b/src/Domain/Common/Providers/Filter.php
index 3499c92f1..c4c20b7e4 100644
--- a/src/Domain/Common/Providers/Filter.php
+++ b/src/Domain/Common/Providers/Filter.php
@@ -54,10 +54,20 @@ public static function getArray(array $array): array
     {
         return array_map(
             static function ($value) {
-                if ($value !== null) {
-                    return is_numeric($value)
-                        ? Filter::getInt($value)
-                        : Filter::getString($value);
+                // Decided by type rather than by `is_numeric()` alone. `getInt()` takes
+                // `int|string` and `getString()` takes `?string`, under strict types, so anything
+                // else — a bool, a float, a nested array, an object — used to reach one of them and
+                // throw a `TypeError`. That is not a hypothetical shape: a JSON body can carry
+                // `[true]` or `[1.5]`, and a form field named `x[a][]` makes one element an array.
+                // Nothing in between caught it, so it surfaced as a 500 whose body named the class,
+                // the method and the server's absolute path. An element this cannot represent is
+                // answered as null, the same as a missing one.
+                if (is_int($value) || (is_string($value) && is_numeric($value))) {
+                    return Filter::getInt($value);
+                }
+
+                if (is_string($value)) {
+                    return Filter::getString($value);
                 }
 
                 return null;
diff --git a/tests/Integration/Infrastructure/Adapter/In/Api/Controllers/ParameterTypesTest.php b/tests/Integration/Infrastructure/Adapter/In/Api/Controllers/ParameterTypesTest.php
index 904b955d6..e3e976d24 100644
--- a/tests/Integration/Infrastructure/Adapter/In/Api/Controllers/ParameterTypesTest.php
+++ b/tests/Integration/Infrastructure/Adapter/In/Api/Controllers/ParameterTypesTest.php
@@ -148,6 +148,46 @@ public function anArrayParameterOfTheWrongTypeIsRefused(): void
         $this->assertBadRequest($r);
     }
 
+    /**
+     * An array whose *elements* are the wrong type is refused the same way.
+     *
+     * `getParamArray()` checked only `is_array()`, so `[true]`, `[1.5]` or `[[1]]` reached
+     * `Filter::getArray()`, which handed each element to `getInt(int|string)` or
+     * `getString(?string)` under strict types. That threw a `TypeError`, and the catch-all answered
+     * it as a 500 with the class, the method and the server's absolute path in the body — the exact
+     * leak the scalar readers above were fixed for, on the one reader this test called "always
+     * right". It was right about the container and never looked inside it.
+     *
+     * @return array<string, array{mixed}>
+     */
+    public static function arrayWithABadElementProvider(): array
+    {
+        return [
+            'a bool' => [[true]],
+            'a float' => [[1.5]],
+            'a nested array' => [[[1]]],
+            'a good id beside a bad one' => [[1, false]],
+        ];
+    }
+
+    #[Test]
+    #[DataProvider('arrayWithABadElementProvider')]
+    public function anArrayParameterWithABadElementIsRefused(array $tagsId): void
+    {
+        $r = $this->callApi(
+            AclActionsInterface::ACCOUNT_CREATE,
+            [
+                'name' => 'an account',
+                'categoryId' => 1,
+                'clientId' => 1,
+                'pass' => 'a-password',
+                'tagsId' => $tagsId,
+            ]
+        );
+
+        $this->assertBadRequest($r);
+    }
+
     /**
      * The control. Every refusal above would be satisfied by an endpoint that had simply stopped
      * accepting anything, so the same call with the right types has to still work.
diff --git a/tests/Unit/Domain/Common/Providers/FilterTest.php b/tests/Unit/Domain/Common/Providers/FilterTest.php
new file mode 100644
index 000000000..791dc09ea
--- /dev/null
+++ b/tests/Unit/Domain/Common/Providers/FilterTest.php
@@ -0,0 +1,82 @@
+<?php
+
+declare(strict_types=1);
+/*
+ * sysPass
+ *
+ * @author nuxsmin
+ * @link https://syspass.org
+ * @copyright 2012-2024, Rubén Domínguez nuxsmin@$syspass.org
+ *
+ * This file is part of sysPass.
+ *
+ * sysPass 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.
+ *
+ * sysPass 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 sysPass.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+namespace SP\Tests\Unit\Domain\Common\Providers;
+
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\Attributes\Group;
+use PHPUnit\Framework\Attributes\Test;
+use PHPUnit\Framework\TestCase;
+use SP\Domain\Common\Providers\Filter;
+
+/**
+ * `Filter::getArray()` is where both doors meet for an array parameter: the API's
+ * `getParamArray()` and the web's `Request::analyzeArray()` both hand their value to it.
+ *
+ * It chose a filter per element by `is_numeric()` alone and passed the element straight on, and
+ * under strict types `getInt()` accepts only `int|string` and `getString()` only `?string`. So a
+ * bool, a float, a nested array or an object threw a `TypeError` that nothing caught, and the
+ * request ended as a 500 naming the class, the method and the server's absolute path. From the web
+ * that needs no more than a form field named `x[a][]`, which makes one element an array; the web's
+ * `analyzeArray()` reads through `InputBag::all()`, which skips Symfony's scalar check.
+ */
+#[Group('unitary')]
+class FilterTest extends TestCase
+{
+    /**
+     * @return array<string, array{mixed}>
+     */
+    public static function unrepresentableElementProvider(): array
+    {
+        return [
+            'a bool' => [true],
+            'a float' => [1.5],
+            'a nested array' => [[1, 2]],
+            'an object' => [new \stdClass()],
+        ];
+    }
+
+    /**
+     * An element the filters cannot represent is answered as null, like a missing one, rather than
+     * throwing.
+     */
+    #[Test]
+    #[DataProvider('unrepresentableElementProvider')]
+    public function anElementItCannotRepresentIsNull(mixed $element): void
+    {
+        self::assertSame([null], Filter::getArray([$element]));
+    }
+
+    /**
+     * The control: the elements it was written for still come through, as the type each filter
+     * gives them.
+     */
+    #[Test]
+    public function idsAndTextStillComeThrough(): void
+    {
+        self::assertSame([5, 7, 'a tag', null], Filter::getArray([5, '7', 'a tag', null]));
+    }
+}