@@ -289,7 +289,14 @@ public function __construct($course, $userid) {
              // hmm, something is wrong - let's fix it
              rebuild_course_cache($course->id);
              $course->sectioncache = $DB->get_field('course', 'sectioncache', array('id'=>$course->id));
 -            $sectioncache = unserialize($course->sectioncache);
 +            // MDL-41896 Error writing to database when multiple sections inline images
 +            // so if we could not store the sectioncache we need to build it again
 +            if (!$course->sectioncache) {
 +                $sectioncache = course_modinfo::build_section_cache($course->id);
 +            } else {
 +                $sectioncache = unserialize($course->sectioncache);
 +            }
 +
              if (!is_array($sectioncache)) {
                  // If it still fails, abort
                  debugging('Problem with "sectioncache" data for this course');
 @@ -1454,9 +1461,21 @@ function rebuild_course_cache($courseid=0, $clearonly=false) {
      foreach ($rs as $course) {
          $modinfo = serialize(get_array_of_activities($course->id));
          $sectioncache = serialize(course_modinfo::build_section_cache($course->id));
 -        $updateobj = (object)array('id' => $course->id,
 -                'modinfo' => $modinfo, 'sectioncache' => $sectioncache);
 -        $DB->update_record("course", $updateobj);
 +        // MDL-41896 Error writing to database when multiple sections inline images
 +        // if updating sectioncache and too big don't store it but build it each time
 +        // Need to find someway of configing this as actual value set in DB e.g. 16M = 16777216
 +        $maxsectioncache=1048576; // 1Mb 
 +        if (strlen($sectioncache)<$maxsectioncache) {
 +            $updateobj = (object)array('id' => $course->id,
 +                    'modinfo' => $modinfo, 'sectioncache' => $sectioncache);
 +            $DB->update_record("course", $updateobj);
 +        } else {
 +            // Too large to cache in sectioncache will need regeneration each time
 +            $updateobj = (object)array('id' => $course->id,
 +                    'modinfo' => $modinfo, 'sectioncache' => null);
 +            $DB->update_record("course", $updateobj);
 +        }
 +
          // update cached global COURSE too ;-)
          if ($course->id == $COURSE->id) {
              $COURSE->modinfo = $modinfo;