diff --git a/blocks/html/tests/privacy/provider_test.php b/blocks/html/tests/privacy/provider_test.php
index f3436a4f1d3..99e062e94df 100644
--- a/blocks/html/tests/privacy/provider_test.php
+++ b/blocks/html/tests/privacy/provider_test.php
@@ -297,6 +297,7 @@ final class provider_test extends \core_privacy\tests\provider_testcase {
         $user = $this->getDataGenerator()->create_user();
         $course = $this->getDataGenerator()->create_course();
         $this->setUser($user);
+        $this->getDataGenerator()->enrol_user($user->id, $course->id, 'editingteacher');
 
         $block = $this->create_course_block($course, $title, $content, $format);
         $context = \context_block::instance($block->instance->id);
@@ -324,6 +325,7 @@ final class provider_test extends \core_privacy\tests\provider_testcase {
         $user = $this->getDataGenerator()->create_user();
         $course = $this->getDataGenerator()->create_course();
         $this->setUser($user);
+        $this->getDataGenerator()->enrol_user($user->id, $course->id, 'editingteacher');
 
         $block = $this->create_course_block($course, $title, $content, $format);
         $context = \context_block::instance($block->instance->id);
@@ -369,6 +371,7 @@ final class provider_test extends \core_privacy\tests\provider_testcase {
         $this->setUser($user2);
 
         $course = $this->getDataGenerator()->create_course();
+        $this->getDataGenerator()->enrol_user($user2->id, $course->id, 'editingteacher');
         $courseblock = $this->create_course_block($course, $title, $content, $blockformat);
         $coursecontext = \context_block::instance($courseblock->instance->id);
 
diff --git a/blocks/tests/externallib_test.php b/blocks/tests/externallib_test.php
index 59fda684872..32fa4f15a13 100644
--- a/blocks/tests/externallib_test.php
+++ b/blocks/tests/externallib_test.php
@@ -44,6 +44,7 @@ final class externallib_test extends externallib_advanced_testcase {
         global $DB, $FULLME;
 
         $this->resetAfterTest(true);
+        $this->setAdminUser();
 
         $user = $this->getDataGenerator()->create_user();
         $course = $this->getDataGenerator()->create_course();
@@ -77,6 +78,7 @@ final class externallib_test extends externallib_advanced_testcase {
         global $DB, $FULLME;
 
         $this->resetAfterTest(true);
+        $this->setAdminUser();
 
         $user = $this->getDataGenerator()->create_user();
 
@@ -141,6 +143,7 @@ final class externallib_test extends externallib_advanced_testcase {
         global $DB, $FULLME;
 
         $this->resetAfterTest(true);
+        $this->setAdminUser();
 
         $user = $this->getDataGenerator()->create_user();
         $course = $this->getDataGenerator()->create_course();
@@ -237,6 +240,7 @@ final class externallib_test extends externallib_advanced_testcase {
         global $DB, $CFG;
 
         $this->resetAfterTest(true);
+        $this->setAdminUser();
 
         // Enable MathJax filter in content and headings.
         $this->configure_filters([
@@ -362,6 +366,7 @@ final class externallib_test extends externallib_advanced_testcase {
     public function test_get_dashboard_blocks_default_dashboard_including_sticky_block(): void {
         global $PAGE, $DB;
         $this->resetAfterTest(true);
+        $this->setAdminUser();
 
         $user = $this->getDataGenerator()->create_user();
         $PAGE->set_url('/my/index.php');    // Need this because some internal API calls require the $PAGE url to be set.
@@ -410,6 +415,7 @@ final class externallib_test extends externallib_advanced_testcase {
     public function test_get_dashboard_blocks_custom_user_dashboard(): void {
         global $PAGE, $DB;
         $this->resetAfterTest(true);
+        $this->setAdminUser();
 
         $user = $this->getDataGenerator()->create_user();
         $PAGE->set_url('/my/index.php');    // Need this because some internal API calls require the $PAGE url to be set.
diff --git a/lang/en/error.php b/lang/en/error.php
index 63fdb30f78f..590e2310a48 100644
--- a/lang/en/error.php
+++ b/lang/en/error.php
@@ -31,6 +31,7 @@ $string['agelocationverificationdisabled'] = 'Age and location verification disa
 $string['authnotexisting'] = 'The autorization plugin doesn\'t exist';
 $string['backupcontainexternal'] = 'This backup file contains external Moodle Network Hosts that are not configured locally';
 $string['backuptablefail'] = 'Backup tables could NOT be set up successfully!';
+$string['blockcannotadd'] = 'Cannot add block';
 $string['blockcannotconfig'] = 'This block does not support global configuration';
 $string['blockcannotinistantiate'] = 'Problem in instantiating block object';
 $string['blockcannotread'] = 'Could not read data for blockid= {$a}';
diff --git a/lib/blocklib.php b/lib/blocklib.php
index 865efe68f05..7dc4ef80a3c 100644
--- a/lib/blocklib.php
+++ b/lib/blocklib.php
@@ -245,18 +245,18 @@ class block_manager {
      * @return boolean - is there one of these blocks in the current page?
      */
     public function is_block_present($blockname) {
-        if (empty($this->blockinstances)) {
+        if (empty($this->birecordsbyregion)) {
             return false;
         }
 
         $requiredbythemeblocks = $this->get_required_by_theme_block_types();
-        foreach ($this->blockinstances as $region) {
+        foreach ($this->birecordsbyregion as $region) {
             foreach ($region as $instance) {
-                if (empty($instance->instance->blockname)) {
+                if (empty($instance->blockname)) {
                     continue;
                 }
-                if ($instance->instance->blockname == $blockname) {
-                    if ($instance->instance->requiredbytheme) {
+                if ($instance->blockname == $blockname) {
+                    if ($instance->requiredbytheme) {
                         if (!in_array($blockname, $requiredbythemeblocks)) {
                             continue;
                         }
@@ -834,6 +834,14 @@ class block_manager {
             $pagetypepattern = $this->page->pagetype;
         }
 
+        if (!empty($this->birecordsbyregion)) {
+            $addableblocks = $this->get_addable_blocks();
+
+            if (!array_key_exists($blockname, $addableblocks)) {
+                throw new moodle_exception('blockcannotadd');
+            }
+        }
+
         $blockinstance = new stdClass;
         $blockinstance->blockname = $blockname;
         $blockinstance->parentcontextid = $this->page->context->id;