diff --git a/backup/controller/backup_controller.class.php b/backup/controller/backup_controller.class.php
index cd124e588b6..e270f9e1f86 100644
--- a/backup/controller/backup_controller.class.php
+++ b/backup/controller/backup_controller.class.php
@@ -110,7 +110,7 @@ class backup_controller extends base_controller {
 
         // By default there is no progress reporter. Interfaces that wish to
         // display progress must set it.
-        $this->progress = new \core\progress\null();
+        $this->progress = new \core\progress\none();
 
         // Instantiate the output_controller singleton and active it if interactive and inmediate
         $oc = output_controller::get_instance();
diff --git a/backup/controller/restore_controller.class.php b/backup/controller/restore_controller.class.php
index 39926492b45..8c72c588359 100644
--- a/backup/controller/restore_controller.class.php
+++ b/backup/controller/restore_controller.class.php
@@ -114,7 +114,7 @@ class restore_controller extends base_controller {
         if ($progress) {
             $this->progress = $progress;
         } else {
-            $this->progress = new \core\progress\null();
+            $this->progress = new \core\progress\none();
         }
         $this->progress->start_progress('Constructing restore_controller');
 
diff --git a/backup/util/dbops/restore_dbops.class.php b/backup/util/dbops/restore_dbops.class.php
index bd00c3221bf..880e75dfbfc 100644
--- a/backup/util/dbops/restore_dbops.class.php
+++ b/backup/util/dbops/restore_dbops.class.php
@@ -123,7 +123,7 @@ abstract class restore_dbops {
 
         // Set up progress tracking (indeterminate).
         if (!$progress) {
-            $progress = new \core\progress\null();
+            $progress = new \core\progress\none();
         }
         $progress->start_progress('Loading inforef.xml file');
 
@@ -430,7 +430,7 @@ abstract class restore_dbops {
 
         // Set up progress tracking (indeterminate).
         if (!$progress) {
-            $progress = new \core\progress\null();
+            $progress = new \core\progress\none();
         }
         $progress->start_progress('Loading users into temporary table');
 
diff --git a/backup/util/ui/restore_ui.class.php b/backup/util/ui/restore_ui.class.php
index 0bb83236d98..d0e2237dfee 100644
--- a/backup/util/ui/restore_ui.class.php
+++ b/backup/util/ui/restore_ui.class.php
@@ -185,11 +185,11 @@ class restore_ui extends base_ui {
      * there are long-running tasks even though there is no restore controller
      * in use.
      *
-     * @return \core\progress\null
+     * @return \core\progress\none
      */
     public function get_progress_reporter() {
         if (!$this->progressreporter) {
-            $this->progressreporter = new \core\progress\null();
+            $this->progressreporter = new \core\progress\none();
         }
         return $this->progressreporter;
     }
diff --git a/backup/util/ui/restore_ui_stage.class.php b/backup/util/ui/restore_ui_stage.class.php
index 5bb40a13780..2917c727f7d 100644
--- a/backup/util/ui/restore_ui_stage.class.php
+++ b/backup/util/ui/restore_ui_stage.class.php
@@ -144,11 +144,11 @@ abstract class restore_ui_independent_stage {
      * in use. There is a similar function in restore_ui. but that class is not
      * used on some stages.
      *
-     * @return \core\progress\null
+     * @return \core\progress\none
      */
     public function get_progress_reporter() {
         if (!$this->progressreporter) {
-            $this->progressreporter = new \core\progress\null();
+            $this->progressreporter = new \core\progress\none();
         }
         return $this->progressreporter;
     }
diff --git a/lib/classes/component.php b/lib/classes/component.php
index 519bbab2198..95f90449171 100644
--- a/lib/classes/component.php
+++ b/lib/classes/component.php
@@ -100,6 +100,9 @@ class core_component {
             $newclassname = self::$classmaprenames[$classname];
             $debugging = "Class '%s' has been renamed for the autoloader and is now deprecated. Please use '%s' instead.";
             debugging(sprintf($debugging, $classname, $newclassname), DEBUG_DEVELOPER);
+            if (PHP_VERSION_ID >= 70000 && preg_match('#\\\null(\\\|$)#', $classname)) {
+                throw new \coding_exception("Cannot alias $classname to $newclassname");
+            }
             class_alias($newclassname, $classname);
             return;
         }
diff --git a/lib/classes/progress/null.php b/lib/classes/progress/none.php
similarity index 73%
rename from lib/classes/progress/null.php
rename to lib/classes/progress/none.php
index f332a30b0f0..4273f34d8a5 100644
--- a/lib/classes/progress/null.php
+++ b/lib/classes/progress/none.php
@@ -14,6 +14,14 @@
 // You should have received a copy of the GNU General Public License
 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
 
+/**
+ * Progress handler that ignores progress entirely.
+ *
+ * @package    core
+ * @copyright  2013 The Open University
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
 namespace core\progress;
 
 defined('MOODLE_INTERNAL') || die();
@@ -21,11 +29,16 @@ defined('MOODLE_INTERNAL') || die();
 /**
  * Progress handler that ignores progress entirely.
  *
- * @package core_progress
+ * @package core
  * @copyright 2013 The Open University
  * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
-class null extends base {
+class none extends base {
+    /**
+     * When progress is updated, do nothing.
+     *
+     * @see \core\progress\base::update_progress()
+     */
     public function update_progress() {
         // Do nothing.
     }
diff --git a/lib/db/renamedclasses.php b/lib/db/renamedclasses.php
index 9ccba774025..537bcf8e84c 100644
--- a/lib/db/renamedclasses.php
+++ b/lib/db/renamedclasses.php
@@ -36,4 +36,5 @@ defined('MOODLE_INTERNAL') || die();
 // The old class name is the key, the new class name is the value.
 // The array must be called $renamedclasses.
 $renamedclasses = array(
+    'core\progress\null' => 'core\progress\none',
 );
diff --git a/lib/upgrade.txt b/lib/upgrade.txt
index 89204013b30..b52ab4ad1ed 100644
--- a/lib/upgrade.txt
+++ b/lib/upgrade.txt
@@ -1,6 +1,10 @@
 This files describes API changes in core libraries and APIs,
 information provided here is intended especially for developers.
 
+=== 3.0 ===
+
+* \core\progress\null is renamed to \core\progress\none for improved PHP7 compatibility as null is a reserved word (see MDL-50453).
+
 === 2.9.1 ===
 
 * New methods grade_grade::get_grade_max() and get_grade_min() must be used rather than directly the public properties rawgrademax and rawgrademin.
diff --git a/mod/quiz/report/statistics/classes/calculator.php b/mod/quiz/report/statistics/classes/calculator.php
index 0e7d127032d..ada45a7d9ee 100644
--- a/mod/quiz/report/statistics/classes/calculator.php
+++ b/mod/quiz/report/statistics/classes/calculator.php
@@ -38,7 +38,7 @@ class calculator {
 
     public function __construct(\core\progress\base $progress = null) {
         if ($progress === null) {
-            $progress = new \core\progress\null();
+            $progress = new \core\progress\none();
         }
         $this->progress = $progress;
     }
diff --git a/mod/quiz/report/statistics/report.php b/mod/quiz/report/statistics/report.php
index fadb7c49615..bc194c41945 100644
--- a/mod/quiz/report/statistics/report.php
+++ b/mod/quiz/report/statistics/report.php
@@ -544,7 +544,7 @@ class quiz_statistics_report extends quiz_default_report {
     public function get_all_stats_and_analysis($quiz, $whichattempts, $whichtries, $groupstudents, $questions, $progress = null) {
 
         if ($progress === null) {
-            $progress = new \core\progress\null();
+            $progress = new \core\progress\none();
         }
 
         $qubaids = quiz_statistics_qubaids_condition($quiz->id, $groupstudents, $whichattempts);
@@ -595,7 +595,7 @@ class quiz_statistics_report extends quiz_default_report {
                 $this->progress = new \core\progress\display_if_slow(get_string('calculatingallstats', 'quiz_statistics'));
                 $this->progress->set_display_names();
             } else {
-                $this->progress = new \core\progress\null();
+                $this->progress = new \core\progress\none();
             }
         }
         return $this->progress;
@@ -613,7 +613,7 @@ class quiz_statistics_report extends quiz_default_report {
     protected function analyse_responses_for_all_questions_and_subquestions($questions, $subquestions, $qubaids,
                                                                             $whichtries, $progress = null) {
         if ($progress === null) {
-            $progress = new \core\progress\null();
+            $progress = new \core\progress\none();
         }
 
         // Starting response analysis tasks.
@@ -643,7 +643,7 @@ class quiz_statistics_report extends quiz_default_report {
             return array();
         }
         if ($progress === null) {
-            $progress = new \core\progress\null();
+            $progress = new \core\progress\none();
         }
         $progress->start_progress('', $countquestions, $countquestions);
         foreach ($questions as $question) {
diff --git a/question/classes/statistics/questions/calculator.php b/question/classes/statistics/questions/calculator.php
index 85c471d946c..567e6e9683f 100644
--- a/question/classes/statistics/questions/calculator.php
+++ b/question/classes/statistics/questions/calculator.php
@@ -68,12 +68,12 @@ class calculator {
      *
      * @param object[] questions to analyze, keyed by slot, also analyses sub questions for random questions.
      *                              we expect some extra fields - slot, maxmark and number on the full question data objects.
-     * @param \core\progress\base|null $progress the element to send progress messages to, default is {@link \core\progress\null}.
+     * @param \core\progress\base|null $progress the element to send progress messages to, default is {@link \core\progress\none}.
      */
     public function __construct($questions, $progress = null) {
 
         if ($progress === null) {
-            $progress = new \core\progress\null();
+            $progress = new \core\progress\none();
         }
         $this->progress = $progress;
         $this->stats = new $this->statscollectionclassname();