diff --git a/lang/en/error.php b/lang/en/error.php
index 590e2310a48..478b7b0af0b 100644
--- a/lang/en/error.php
+++ b/lang/en/error.php
@@ -552,6 +552,7 @@ $string['sessionipnomatch2'] = '<p>Sorry, but your IP number seems to have chang
 $string['sessioncannotobtainlock'] = '<p>Unable to obtain lock for session id {$a->id} within {$a->acquiretimeout}.</p>
 <p>It is likely that another page ({$a->whohaslock}) is still running in another browser tab, or it did not release the lock due to an error.</p>
 <p>You can wait until the session lock timeout ({$a->lockexpire}) or you can restart your browser session. If this error persists, please notify the server administrator.</p>';
+$string['sessionstarterror'] = 'Couldn\'t start session. Please try again later.';
 $string['shortnametaken'] = 'Short name is already used for another course ({$a})';
 $string['sitepolicynotagreed'] = 'Site policy not agreed: <a href="{$a}">Click here to open the site policy.</a>';
 $string['scheduledbackupsdisabled'] = 'Scheduled backups have been disabled by the server admin';
diff --git a/lib/classes/session/manager.php b/lib/classes/session/manager.php
index 7070ec9c42d..e1f6dc88453 100644
--- a/lib/classes/session/manager.php
+++ b/lib/classes/session/manager.php
@@ -153,7 +153,7 @@ class manager {
 
             if (!self::$handler->start()) {
                 // Could not successfully start/recover session.
-                throw new \core\session\exception(get_string('servererror'));
+                throw new \core\session\exception('sessionstarterror', 'error');
             }
 
             if ($requireslock) {