diff --git a/course/externallib.php b/course/externallib.php
index 550cc920e24..8344993c085 100644
--- a/course/externallib.php
+++ b/course/externallib.php
@@ -142,16 +142,6 @@ class core_course_external extends external_api {
         //retrieve the course
         $course = $DB->get_record('course', array('id' => $params['courseid']), '*', MUST_EXIST);
 
-        if ($course->id != SITEID) {
-            // Check course format exist.
-            if (!file_exists($CFG->dirroot . '/course/format/' . $course->format . '/lib.php')) {
-                throw new moodle_exception('cannotgetcoursecontents', 'webservice', '', null,
-                                            get_string('courseformatnotfound', 'error', $course->format));
-            } else {
-                require_once($CFG->dirroot . '/course/format/' . $course->format . '/lib.php');
-            }
-        }
-
         // now security checks
         $context = context_course::instance($course->id, IGNORE_MISSING);
         try {
diff --git a/course/tests/externallib_test.php b/course/tests/externallib_test.php
index 79a7c5104be..3c5f18fa616 100644
--- a/course/tests/externallib_test.php
+++ b/course/tests/externallib_test.php
@@ -1715,6 +1715,23 @@ class externallib_test extends externallib_advanced_testcase {
         }
     }
 
+    /**
+     * Test get_course_contents for courses with invalid course format.
+     */
+    public function test_get_course_contents_invalid_format() {
+        global $DB;
+        $this->resetAfterTest();
+
+        list($course, $forumcm, $datacm, $pagecm, $labelcm, $urlcm) = $this->prepare_get_course_contents_test();
+
+        $DB->set_field('course', 'format', 'fakeformat', ['id' => $course->id]);
+
+        // WS should falback to default course format (topics) and avoid exceptions (but debugging will happen).
+        $result = core_course_external::get_course_contents($course->id);
+        $this->assertDebuggingCalled();
+        $result = external_api::clean_returnvalue(core_course_external::get_course_contents_returns(), $result);
+    }
+
     /**
      * Test duplicate_course
      */
diff --git a/course/upgrade.txt b/course/upgrade.txt
index e1dd6d8ab4d..d6d60e0ddb9 100644
--- a/course/upgrade.txt
+++ b/course/upgrade.txt
@@ -10,6 +10,7 @@ information provided here is intended especially for developers.
 * The method `make_categories_options`, deprecated since 3.10, has been removed
 * External function core_course_external::get_courses_by_field and core_course_external::search_courses now return a field
 called "courseimage" containing a URL pointing to the course image.
+* External function core_course_external::get_course_contents() does not throw exceptions for invalid course formats anymore.
 
 === 4.1 ===
 * The function course_modchooser() has been finally deprecated and can not be used anymore. Please use
diff --git a/lang/en/deprecated.txt b/lang/en/deprecated.txt
index 7c8d426160e..32eb96d0d18 100644
--- a/lang/en/deprecated.txt
+++ b/lang/en/deprecated.txt
@@ -90,3 +90,5 @@ studentsperpage,core_grades
 studentsperpage_help,core_grades
 type_contentbank,core_plugin
 type_contentbank_plural,core_plugin
+missingversionfile,core_webservice
+cannotgetcoursecontents,core_webservice
diff --git a/lang/en/webservice.php b/lang/en/webservice.php
index 8636e501e5c..a7d88049f16 100644
--- a/lang/en/webservice.php
+++ b/lang/en/webservice.php
@@ -42,7 +42,6 @@ $string['arguments'] = 'Arguments';
 $string['authmethod'] = 'Authentication method';
 $string['callablefromajax'] = 'Callable from AJAX';
 $string['cannotcreatetoken'] = 'No permission to create web service token for the service {$a}.';
-$string['cannotgetcoursecontents'] = 'Cannot get course contents';
 $string['configwebserviceplugins'] = 'For security reasons, only protocols that are in use should be enabled.';
 $string['context'] = 'Context';
 $string['createservicedescription'] = 'A service is a set of web service functions. You will allow the user to access to a new service. On the <strong>Add service</strong> page check \'Enable\' and \'Authorised users\' options. Select \'No required capability\'.';
@@ -126,7 +125,6 @@ $string['missingcaps_help'] = 'List of capabilities declared by the service whic
 $string['missingpassword'] = 'Missing password';
 $string['missingrequiredcapability'] = 'The capability {$a} is required.';
 $string['missingusername'] = 'Missing username';
-$string['missingversionfile'] = 'Coding error: version.php file is missing for the component {$a}';
 $string['nameexists'] = 'This name is already in use by another service';
 $string['nocapabilitytouseparameter'] = 'The user does not have the required capability to use the parameter {$a}';
 $string['nofunctions'] = 'This service has no functions.';
@@ -235,3 +233,6 @@ $string['wsusername'] = 'Web service username';
 // Deprecated since Moodle 3.11.
 $string['usernameoridnousererror'] = 'No users were found with this username/user id.';
 $string['usernameoridoccurenceerror'] = 'More than one user was found with this username. Please enter the user id.';
+// Deprecated since Moodle 4.2.
+$string['missingversionfile'] = 'Coding error: version.php file is missing for the component {$a}';
+$string['cannotgetcoursecontents'] = 'Cannot get course contents';
diff --git a/webservice/externallib.php b/webservice/externallib.php
index 591debdf9b7..95ec4cbb8d0 100644
--- a/webservice/externallib.php
+++ b/webservice/externallib.php
@@ -142,9 +142,8 @@ class core_webservice_external extends \core_external\external_api {
                         $version = $componentversions[$function->component];
                     }
                 } else {
-                    // Function component should always have a version.php,
-                    // otherwise the function should have been described with component => 'moodle'.
-                    throw new moodle_exception('missingversionfile', 'webservice', '', $function->component);
+                    // Ignore this component or plugin, it was probably incorrectly uninstalled.
+                    continue;
                 }
             }
             $functioninfo['version'] = $version;
diff --git a/webservice/tests/externallib_test.php b/webservice/tests/externallib_test.php
index a46a32ec78a..d4f9e425c86 100644
--- a/webservice/tests/externallib_test.php
+++ b/webservice/tests/externallib_test.php
@@ -208,4 +208,66 @@ class externallib_test extends externallib_advanced_testcase {
         $this->assertEquals(PHP_INT_MAX, $result['userquota']);
     }
 
+    /**
+     * Test get_site_info with missing components.
+     */
+    public function test_get_site_missing_components() {
+        global $USER, $DB;
+
+        $this->resetAfterTest(true);
+        $this->setAdminUser();
+
+        // Add a web service and token.
+        $webservice = new \stdClass();
+        $webservice->name = 'Test web service';
+        $webservice->enabled = true;
+        $webservice->restrictedusers = false;
+        $webservice->component = 'moodle';
+        $webservice->timecreated = time();
+        $webservice->downloadfiles = true;
+        $webservice->uploadfiles = true;
+        $externalserviceid = $DB->insert_record('external_services', $webservice);
+
+        // Add a function to the service (missing plugin).
+        $DB->insert_record('external_functions',
+            [
+                'component' => 'mod_random',
+                'name' => 'mod_random_get_info'
+            ]
+        );
+
+        // Insert one from missing component.
+        $DB->insert_record('external_services_functions',
+            [
+                'externalserviceid' => $externalserviceid,
+                'functionname' => 'mod_random_get_info'
+            ]
+        );
+        // Insert a core one.
+        $DB->insert_record('external_services_functions',
+            [
+                'externalserviceid' => $externalserviceid,
+                'functionname' => 'core_user_get_users'
+            ]
+        );
+
+        $_POST['wstoken'] = 'testtoken';
+        $externaltoken = new \stdClass();
+        $externaltoken->token = 'testtoken';
+        $externaltoken->tokentype = 0;
+        $externaltoken->userid = $USER->id;
+        $externaltoken->externalserviceid = $externalserviceid;
+        $externaltoken->contextid = 1;
+        $externaltoken->creatorid = $USER->id;
+        $externaltoken->timecreated = time();
+        $DB->insert_record('external_tokens', $externaltoken);
+
+        // Execution should complete.
+        $result = \core_webservice_external::get_site_info();
+        $result = external_api::clean_returnvalue(\core_webservice_external::get_site_info_returns(), $result);
+        // Check we ignore the missing component function.
+        $this->assertCount(1, $result['functions']);
+        $this->assertEquals('core_user_get_users', $result['functions'][0]['name']);
+    }
+
 }
diff --git a/webservice/upgrade.txt b/webservice/upgrade.txt
index 8662cd753ed..5d0bc2bc2d8 100644
--- a/webservice/upgrade.txt
+++ b/webservice/upgrade.txt
@@ -3,6 +3,10 @@ information provided here is intended especially for developers.
 
 This information is intended for authors of webservices, not people writing webservice clients.
 
+=== 4.2 ===
+
+* External function core_webservice_external::get_site_info() does not throw exceptions for missing components anymore.
+
 === 4.1 ===
 
 * The XMLRPC webservice (protocol) has been completely removed. It's now available in the plugins directory.