diff --git a/mod/data/classes/external.php b/mod/data/classes/external.php
index 9e65b35192f..4568cb7c76d 100644
--- a/mod/data/classes/external.php
+++ b/mod/data/classes/external.php
@@ -982,6 +982,12 @@ class mod_data_external extends external_api {
         $fieldnotifications = array();
 
         list($database, $course, $cm, $context) = self::validate_database($params['databaseid']);
+
+        $fields = $DB->get_records('data_fields', ['dataid' => $database->id]);
+        if (empty($fields)) {
+            throw new moodle_exception('nofieldindatabase', 'data');
+        }
+
         // Check database is open in time.
         data_require_time_available($database, null, $context);
 
@@ -1009,7 +1015,6 @@ class mod_data_external extends external_api {
             $datarecord->{'field_' . $data['fieldid'] . $subfield} = json_decode($data['value']);
         }
         // Validate to ensure that enough data was submitted.
-        $fields = $DB->get_records('data_fields', array('dataid' => $database->id));
         $processeddata = data_process_submission($database, $fields, $datarecord);
 
         // Format notifications.
diff --git a/mod/data/lib.php b/mod/data/lib.php
index a1820a6bc14..631869b7ab9 100644
--- a/mod/data/lib.php
+++ b/mod/data/lib.php
@@ -2139,7 +2139,12 @@ function data_print_header($course, $cm, $data, $currenttab='', string $actionba
  * @return bool
  */
 function data_user_can_add_entry($data, $currentgroup, $groupmode, $context = null) {
-    global $USER;
+    global $DB;
+
+    // Don't let add entry to a database that has no fields.
+    if (!$DB->record_exists('data_fields', ['dataid' => $data->id])) {
+        return false;
+    }
 
     if (empty($context)) {
         $cm = get_coursemodule_from_instance('data', $data->id, 0, false, MUST_EXIST);
diff --git a/mod/data/tests/externallib_test.php b/mod/data/tests/externallib_test.php
index d13618af310..98b43bdad26 100644
--- a/mod/data/tests/externallib_test.php
+++ b/mod/data/tests/externallib_test.php
@@ -113,6 +113,21 @@ class externallib_test extends externallib_advanced_testcase {
         groups_add_member($this->group2, $this->student3);
     }
 
+    /**
+     * Add a test field to the database activity instance to be used in the unit tests.
+     *
+     * @return \data_field_base
+     */
+    protected function add_test_field(): \data_field_base {
+        $generator = $this->getDataGenerator()->get_plugin_generator('mod_data');
+
+        // Add fields.
+        $fieldrecord = new \stdClass();
+        $fieldrecord->name = 'Test field'; // Identifier of the records for testing.
+        $fieldrecord->type = 'text';
+        return $generator->create_field($fieldrecord, $this->database);
+    }
+
     /**
      * Test get databases by courses
      */
@@ -321,6 +336,10 @@ class externallib_test extends externallib_advanced_testcase {
      */
     public function test_get_data_access_information_student() {
         global $DB;
+
+        // Add a field to database to let users add new entries.
+        $this->add_test_field();
+
         // Modify the database to add access restrictions.
         $this->database->timeavailablefrom = time() + DAYSECS;
         $this->database->requiredentries = 2;
@@ -350,6 +369,10 @@ class externallib_test extends externallib_advanced_testcase {
      */
     public function test_get_data_access_information_teacher() {
         global $DB;
+
+        // Add a field to database to let users add new entries.
+        $this->add_test_field();
+
         // Modify the database to add access restrictions.
         $this->database->timeavailablefrom = time() + DAYSECS;
         $this->database->requiredentries = 2;
@@ -380,6 +403,9 @@ class externallib_test extends externallib_advanced_testcase {
     public function test_get_data_access_information_groups() {
         global $DB;
 
+        // Add a field to database to let users add new entries.
+        $this->add_test_field();
+
         $DB->set_field('course', 'groupmode', VISIBLEGROUPS, ['id' => $this->course->id]);
 
         // Check I can see my group.
@@ -1088,6 +1114,10 @@ class externallib_test extends externallib_advanced_testcase {
      * Test add_entry empty_form.
      */
     public function test_add_entry_empty_form() {
+
+        // Add a field to database to let users add new entries.
+        $this->add_test_field();
+
         $result = mod_data_external::add_entry($this->database->id, 0, []);
         $result = \external_api::clean_returnvalue(mod_data_external::add_entry_returns(), $result);
         $this->assertEquals(0, $result['newentryid']);
@@ -1133,12 +1163,26 @@ class externallib_test extends externallib_advanced_testcase {
      * Test add_entry invalid group.
      */
     public function test_add_entry_invalid_group() {
+
+        // Add a field to database to let users add new entries.
+        $this->add_test_field();
+
         $this->setUser($this->student1);
         $this->expectExceptionMessage(get_string('noaccess', 'data'));
         $this->expectException('moodle_exception');
         mod_data_external::add_entry($this->database->id, $this->group2->id, []);
     }
 
+    /**
+     * Test add_entry for an empty database (no fields).
+     *
+     * @covers \mod_data\mod_data_external::add_entry
+     */
+    public function test_add_entry_empty_database() {
+        $this->expectException('moodle_exception');
+        mod_data_external::add_entry($this->database->id, 0, []);
+    }
+
     /**
      * Test update_entry.
      */
diff --git a/mod/data/upgrade.txt b/mod/data/upgrade.txt
index c7659d1baea..f3e4bcabc0f 100644
--- a/mod/data/upgrade.txt
+++ b/mod/data/upgrade.txt
@@ -13,6 +13,8 @@ information provided here is intended especially for developers.
   - data_presets_generate_xml
   - data_presets_save
   - is_directory_a_preset
+* mod_data_external::add_entry() function throws an error when trying to add an entry to a database with no field created.
+* data_user_can_add_entry() function returns false for any user if there is no field created on the database.
 
 === 3.7 ===
 * External functions get_entries, get_entry and search_entries now return an additional field "tags" containing the entry tags.