diff --git a/lib/classes/exception/coding_exception.php b/lib/classes/exception/coding_exception.php
index 94936bea7fa..677620df799 100644
--- a/lib/classes/exception/coding_exception.php
+++ b/lib/classes/exception/coding_exception.php
@@ -25,11 +25,12 @@
  */
 class coding_exception extends moodle_exception {
     /**
-     * Constructor
+     * Constructor.
+     *
      * @param string $hint short description of problem
      * @param string $debuginfo detailed information how to fix problem
      */
-    function __construct($hint, $debuginfo=null) {
+    public function __construct($hint, $debuginfo = null) {
         parent::__construct('codingerror', 'debug', '', $hint, $debuginfo);
     }
 }
diff --git a/lib/classes/exception/file_serving_exception.php b/lib/classes/exception/file_serving_exception.php
index f60c21d0e77..adccfa1a340 100644
--- a/lib/classes/exception/file_serving_exception.php
+++ b/lib/classes/exception/file_serving_exception.php
@@ -25,10 +25,11 @@
  */
 class file_serving_exception extends moodle_exception {
     /**
-     * Constructor
+     * Constructor.
+     *
      * @param string $debuginfo optional more detailed information
      */
-    function __construct($debuginfo = NULL) {
-        parent::__construct('cannotservefile', 'error', '', NULL, $debuginfo);
+    public function __construct($debuginfo = null) {
+        parent::__construct('cannotservefile', 'error', '', null, $debuginfo);
     }
 }
diff --git a/lib/classes/exception/invalid_dataroot_permissions.php b/lib/classes/exception/invalid_dataroot_permissions.php
index cb7feeaa079..2f39de58fee 100644
--- a/lib/classes/exception/invalid_dataroot_permissions.php
+++ b/lib/classes/exception/invalid_dataroot_permissions.php
@@ -25,10 +25,11 @@
  */
 class invalid_dataroot_permissions extends moodle_exception {
     /**
-     * Constructor
+     * Constructor.
+     *
      * @param string $debuginfo optional more detailed information
      */
-    function __construct($debuginfo = NULL) {
-        parent::__construct('invaliddatarootpermissions', 'error', '', NULL, $debuginfo);
+    public function __construct($debuginfo = null) {
+        parent::__construct('invaliddatarootpermissions', 'error', '', null, $debuginfo);
     }
 }
diff --git a/lib/classes/exception/invalid_parameter_exception.php b/lib/classes/exception/invalid_parameter_exception.php
index a8b3d58608f..5aa8a4f1a05 100644
--- a/lib/classes/exception/invalid_parameter_exception.php
+++ b/lib/classes/exception/invalid_parameter_exception.php
@@ -27,10 +27,11 @@
  */
 class invalid_parameter_exception extends moodle_exception {
     /**
-     * Constructor
+     * Constructor.
+     *
      * @param string $debuginfo some detailed information
      */
-    function __construct($debuginfo=null) {
+    public function __construct($debuginfo = null) {
         parent::__construct('invalidparameter', 'debug', '', null, $debuginfo);
     }
 }
diff --git a/lib/classes/exception/invalid_response_exception.php b/lib/classes/exception/invalid_response_exception.php
index 22317ee6a7e..03082713e3d 100644
--- a/lib/classes/exception/invalid_response_exception.php
+++ b/lib/classes/exception/invalid_response_exception.php
@@ -19,13 +19,19 @@
  * This exception is not supposed to be thrown when processing
  * user submitted data in forms. It is more suitable
  * for WS and other low level stuff.
+ *
+ * @package    core
+ * @subpackage lib
+ * @copyright  Jerome Mounerac
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class invalid_response_exception extends moodle_exception {
     /**
-     * Constructor
+     * Constructor.
+     *
      * @param string $debuginfo some detailed information
      */
-    function __construct($debuginfo=null) {
+    public function __construct($debuginfo = null) {
         parent::__construct('invalidresponse', 'debug', '', null, $debuginfo);
     }
 }
diff --git a/lib/classes/exception/invalid_state_exception.php b/lib/classes/exception/invalid_state_exception.php
index 09aa18a5625..47ee19a5aff 100644
--- a/lib/classes/exception/invalid_state_exception.php
+++ b/lib/classes/exception/invalid_state_exception.php
@@ -28,11 +28,12 @@
  */
 class invalid_state_exception extends moodle_exception {
     /**
-     * Constructor
+     * Constructor.
+     *
      * @param string $hint short description of problem
      * @param string $debuginfo optional more detailed information
      */
-    function __construct($hint, $debuginfo=null) {
+    public function __construct($hint, $debuginfo = null) {
         parent::__construct('invalidstatedetected', 'debug', '', $hint, $debuginfo);
     }
 }
diff --git a/lib/classes/exception/moodle_exception.php b/lib/classes/exception/moodle_exception.php
index 10c67d661f7..cff748790bc 100644
--- a/lib/classes/exception/moodle_exception.php
+++ b/lib/classes/exception/moodle_exception.php
@@ -26,41 +26,35 @@
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class moodle_exception extends \Exception {
-
-    /**
-     * @var string The name of the string from error.php to print
-     */
+    /** @var string The name of the string from error.php to print */
     public $errorcode;
 
-    /**
-     * @var string The name of module
-     */
+    /** @var string The name of module */
     public $module;
 
-    /**
-     * @var mixed Extra words and phrases that might be required in the error string
-     */
+    /** @var mixed Extra words and phrases that might be required in the error string */
     public $a;
 
     /**
-     * @var string The url where the user will be prompted to continue. If no url is provided the user will be directed to the site index page.
+     * The url where the user will be prompted to continue. If no url is provided the user will be directed to the site index page.
+     *
+     * @var string
      */
     public $link;
 
-    /**
-     * @var string Optional information to aid the debugging process
-     */
+    /** @var string Optional information to aid the debugging process */
     public $debuginfo;
 
     /**
      * Constructor
      * @param string $errorcode The name of the string from error.php to print
      * @param string $module name of module
-     * @param string $link The url where the user will be prompted to continue. If no url is provided the user will be directed to the site index page.
+     * @param string $link The url where the user will be prompted to continue.
+     * If no url is provided the user will be directed to the site index page.
      * @param mixed $a Extra words and phrases that might be required in the error string
      * @param string $debuginfo optional debugging information
      */
-    function __construct($errorcode, $module='', $link='', $a=NULL, $debuginfo=null) {
+    public function __construct($errorcode, $module = '', $link = '', $a = null, $debuginfo = null) {
         global $CFG;
 
         if (empty($module) || $module == 'moodle' || $module == 'core') {
@@ -95,11 +89,11 @@ class moodle_exception extends \Exception {
             }
         }
 
-        if (!$haserrorstring and $isinphpunittest) {
+        if (!$haserrorstring && $isinphpunittest) {
             // Append the contents of $a to $debuginfo so helpful information isn't lost.
             // This emulates what {@link get_exception_info()} does. Unfortunately that
             // function is not used by phpunit.
-            $message .= PHP_EOL.'$a contents: '.print_r($a, true);
+            $message .= PHP_EOL . '$a contents: ' . print_r($a, true); // phpcs:ignore moodle.PHP.ForbiddenFunctions.Found
         }
 
         parent::__construct($message, 0);
diff --git a/lib/classes/exception/require_login_exception.php b/lib/classes/exception/require_login_exception.php
index b66dd09b093..5eadb688e2f 100644
--- a/lib/classes/exception/require_login_exception.php
+++ b/lib/classes/exception/require_login_exception.php
@@ -19,16 +19,17 @@
  *
  * This exception is thrown from require_login()
  *
- * @package    core_access
+ * @package    core
  * @copyright  2010 Petr Skoda  {@link http://skodak.org}
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class require_login_exception extends moodle_exception {
     /**
-     * Constructor
+     * Constructor.
+     *
      * @param string $debuginfo Information to aid the debugging process
      */
-    function __construct($debuginfo) {
-        parent::__construct('requireloginerror', 'error', '', NULL, $debuginfo);
+    public function __construct($debuginfo) {
+        parent::__construct('requireloginerror', 'error', '', null, $debuginfo);
     }
 }
diff --git a/lib/classes/exception/require_login_session_timeout_exception.php b/lib/classes/exception/require_login_session_timeout_exception.php
index b8519c4a2ac..56c70509a61 100644
--- a/lib/classes/exception/require_login_session_timeout_exception.php
+++ b/lib/classes/exception/require_login_session_timeout_exception.php
@@ -19,7 +19,7 @@
  *
  * This exception is thrown from require_login()
  *
- * @package    core_access
+ * @package    core
  * @copyright  2015 Andrew Nicols <andrew@nicols.co.uk>
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
diff --git a/lib/classes/exception/required_capability_exception.php b/lib/classes/exception/required_capability_exception.php
index 9ea1827c3dd..da8a9062d68 100644
--- a/lib/classes/exception/required_capability_exception.php
+++ b/lib/classes/exception/required_capability_exception.php
@@ -18,22 +18,24 @@
  * Exceptions indicating user does not have permissions to do something
  * and the execution can not continue.
  *
- * @package    core_access
+ * @package    core
  * @copyright  2009 Petr Skoda  {@link http://skodak.org}
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class required_capability_exception extends moodle_exception {
     /**
-     * Constructor
+     * Constructor.
+     *
      * @param context $context The context used for the capability check
      * @param string $capability The required capability
      * @param string $errormessage The error message to show the user
      * @param string $stringfile
      */
-    function __construct($context, $capability, $errormessage, $stringfile) {
+    public function __construct($context, $capability, $errormessage, $stringfile) {
         $capabilityname = get_capability_string($capability);
-        if ($context->contextlevel == CONTEXT_MODULE and preg_match('/:view$/', $capability)) {
-            // we can not go to mod/xx/view.php because we most probably do not have cap to view it, let's go to course instead
+        if ($context->contextlevel == CONTEXT_MODULE && preg_match('/:view$/', $capability)) {
+            // Cannot redirect to mod/xx/view.php because we most probably do not have cap to view it.
+            // Redirect to the course instead.
             $parentcontext = $context->get_parent_context();
             $link = $parentcontext->get_url();
         } else {
diff --git a/lib/classes/exception/webservice_parameter_exception.php b/lib/classes/exception/webservice_parameter_exception.php
index ef6917cc4a2..a2b5165ea8c 100644
--- a/lib/classes/exception/webservice_parameter_exception.php
+++ b/lib/classes/exception/webservice_parameter_exception.php
@@ -21,15 +21,19 @@
  * @deprecated since Moodle 2.2 - use moodle exception instead
  * This exception must be thrown to the web service client when a web service parameter is invalid
  * The error string is gotten from webservice.php
+ * @package    core
+ * @copyright  Jerome Mouneray
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class webservice_parameter_exception extends moodle_exception {
     /**
-     * Constructor
+     * Constructor.
+     *
      * @param string $errorcode The name of the string from webservice.php to print
      * @param string $a The name of the parameter
      * @param string $debuginfo Optional information to aid debugging
      */
-    function __construct($errorcode=null, $a = '', $debuginfo = null) {
+    public function __construct($errorcode = null, $a = '', $debuginfo = null) {
         parent::__construct($errorcode, 'webservice', '', $a, $debuginfo);
     }
 }
diff --git a/lib/classes/output/bootstrap_renderer.php b/lib/classes/output/bootstrap_renderer.php
index 6bc8e1893e2..8ad880d588f 100644
--- a/lib/classes/output/bootstrap_renderer.php
+++ b/lib/classes/output/bootstrap_renderer.php
@@ -55,13 +55,15 @@ class bootstrap_renderer {
     /**
      * Handles re-entrancy. Without this, errors or debugging output that occur
      * during the initialisation of $OUTPUT, cause infinite recursion.
-     * @var boolean
+     *
+     * @var bool
      */
     protected $initialising = false;
 
     /**
-     * Have we started output yet?
-     * @return boolean true if the header has been printed.
+     * Whether output has started yet.
+     *
+     * @return bool true if the header has been printed.
      */
     public function has_started() {
         return false;
@@ -69,42 +71,45 @@ class bootstrap_renderer {
 
     /**
      * Constructor - to be used by core code only.
+     *
      * @param string $method The method to call
      * @param array $arguments Arguments to pass to the method being called
      * @return string
      */
     public function __call($method, $arguments) {
+        // phpcs:disable moodle.PHP.ForbiddenGlobalUse.BadGlobal
         global $OUTPUT, $PAGE;
 
         $recursing = false;
         if ($method == 'notification') {
             // Catch infinite recursion caused by debugging output during print_header.
+            // phpcs:ignore PHPCompatibility.FunctionUse.ArgumentFunctionsReportCurrentValue.NeedsInspection
             $backtrace = debug_backtrace();
             array_shift($backtrace);
             array_shift($backtrace);
             $recursing = is_early_init($backtrace);
         }
 
-        $earlymethods = array(
+        $earlymethods = [
             'fatal_error' => 'early_error',
             'notification' => 'early_notification',
-        );
+        ];
 
         // If lib/outputlib.php has been loaded, call it.
         if (!empty($PAGE) && !$recursing) {
             if (array_key_exists($method, $earlymethods)) {
-                //prevent PAGE->context warnings - exceptions might appear before we set any context
+                // Prevent PAGE->context warnings - exceptions might appear before we set any context.
                 $PAGE->set_context(null);
             }
             $PAGE->initialise_theme_and_output();
-            return call_user_func_array(array($OUTPUT, $method), $arguments);
+            return call_user_func_array([$OUTPUT, $method], $arguments);
         }
 
         $this->initialising = true;
 
         // Too soon to initialise $OUTPUT, provide a couple of key methods.
         if (array_key_exists($method, $earlymethods)) {
-            return call_user_func_array(array('bootstrap_renderer', $earlymethods[$method]), $arguments);
+            return call_user_func_array(['bootstrap_renderer', $earlymethods[$method]], $arguments);
         }
 
         throw new coding_exception('Attempt to start output before enough information is known to initialise the theme.');
@@ -112,7 +117,7 @@ class bootstrap_renderer {
 
     /**
      * Returns nicely formatted error message in a div box.
-     * @static
+     *
      * @param string $message error message
      * @param ?string $moreinfourl (ignored in early errors)
      * @param ?string $link (ignored in early errors)
@@ -137,10 +142,13 @@ class bootstrap_renderer {
                 } else {
                     // Because weblib is not available for these early errors, we
                     // just duplicate s() code here to be safe.
-                    $debuginfo = preg_replace('/&amp;#(\d+|x[0-9a-f]+);/i', '&#$1;',
-                    htmlspecialchars($debuginfo, ENT_QUOTES | ENT_HTML401 | ENT_SUBSTITUTE));
+                    $debuginfo = preg_replace(
+                        '/&amp;#(\d+|x[0-9a-f]+);/i',
+                        '&#$1;',
+                        htmlspecialchars($debuginfo, ENT_QUOTES | ENT_HTML401 | ENT_SUBSTITUTE)
+                    );
                 }
-                $debuginfo = str_replace("\n", '<br />', $debuginfo); // keep newlines
+                $debuginfo = str_replace("\n", '<br />', $debuginfo); // Keep newlines.
                 $content .= '<div class="notifytiny">Debug info: ' . $debuginfo . '</div>';
             }
             if (!empty($backtrace)) {
@@ -153,7 +161,7 @@ class bootstrap_renderer {
 
     /**
      * This function should only be called by this class, or from exception handlers
-     * @static
+     *
      * @param string $message error message
      * @param string $moreinfourl (ignored in early errors)
      * @param string $link (ignored in early errors)
@@ -166,7 +174,7 @@ class bootstrap_renderer {
 
         if (CLI_SCRIPT) {
             echo "!!! $message !!!\n";
-            if (!empty($CFG->debug) and $CFG->debug >= DEBUG_DEVELOPER) {
+            if (!empty($CFG->debug) && $CFG->debug >= DEBUG_DEVELOPER) {
                 if (!empty($debuginfo)) {
                     echo "\nDebug info: $debuginfo";
                 }
@@ -175,13 +183,12 @@ class bootstrap_renderer {
                 }
             }
             return;
-
         } else if (AJAX_SCRIPT) {
             $e = new stdClass();
             $e->error      = $message;
-            $e->stacktrace = NULL;
-            $e->debuginfo  = NULL;
-            if (!empty($CFG->debug) and $CFG->debug >= DEBUG_DEVELOPER) {
+            $e->stacktrace = null;
+            $e->debuginfo  = null;
+            if (!empty($CFG->debug) && $CFG->debug >= DEBUG_DEVELOPER) {
                 if (!empty($debuginfo)) {
                     $e->debuginfo = $debuginfo;
                 }
@@ -200,7 +207,7 @@ class bootstrap_renderer {
         $protocol = (isset($_SERVER['SERVER_PROTOCOL']) ? $_SERVER['SERVER_PROTOCOL'] : 'HTTP/1.0');
         @header($protocol . ' 500 Internal Server Error');
 
-        // better disable any caching
+        // Better disable any caching.
         @header('Content-Type: text/html; charset=utf-8');
         @header('X-UA-Compatible: IE=edge');
         @header('Cache-Control: no-store, no-cache, must-revalidate');
@@ -222,7 +229,7 @@ class bootstrap_renderer {
 
     /**
      * Early notification message
-     * @static
+     *
      * @param string $message
      * @param string $classes usually notifyproblem or notifysuccess
      * @return string
@@ -233,26 +240,27 @@ class bootstrap_renderer {
 
     /**
      * Page should redirect message.
-     * @static
+     *
      * @param string $encodedurl redirect url
      * @return string
      */
     public static function plain_redirect_message($encodedurl) {
-        $message = '<div style="margin-top: 3em; margin-left:auto; margin-right:auto; text-align:center;">' . get_string('pageshouldredirect') . '<br /><a href="'.
-                $encodedurl .'">'. get_string('continue') .'</a></div>';
+        $message = '<div style="margin-top: 3em; margin-left:auto; margin-right:auto; text-align:center;">';
+        $message .= get_string('pageshouldredirect') . '<br /><a href="';
+        $message .= $encodedurl . '">' . get_string('continue') . '</a></div>';
         return self::plain_page(get_string('redirect'), $message);
     }
 
     /**
-     * Early redirection page, used before full init of $PAGE global
-     * @static
+     * Early redirection page, used before full init of $PAGE global.
+     *
      * @param string $encodedurl redirect url
      * @param string $message redirect message
      * @param int $delay time in seconds
      * @return string redirect page
      */
     public static function early_redirect_message($encodedurl, $message, $delay) {
-        $meta = '<meta http-equiv="refresh" content="'. $delay .'; url='. $encodedurl .'" />';
+        $meta = '<meta http-equiv="refresh" content="' . $delay . '; url=' . $encodedurl . '" />';
         $content = self::early_error_content($message, null, null, null);
         $content .= self::plain_redirect_message($encodedurl);
 
@@ -261,7 +269,7 @@ class bootstrap_renderer {
 
     /**
      * Output basic html page.
-     * @static
+     *
      * @param string $title page title
      * @param string $content page content
      * @param string $meta meta tag