System Status Page Blank after Upgrade
Here's one answer that fixed my problem (see my comment above).  The cause was that when I created the Drupal system I just used the domain name without the www.  But Civi was loaded with www.  This is an old problem and I'm a bit ashamed to admit I made this mistake again!  But if your system has this mismatch then system status won't work.  Fix was to change the base url in Drupal.