Maybe another clue: I tried to activate Akismet first, and noticed it was still the old version; plus, clicking “activate” produced an error page, again referencing the cache. So I deleted my cache plugin, and then uploaded the current version of Akismet. Now I’m getting:
Warning: main(/home/content/e/l/v//html/wp-content/advanced-cache.php): failed to open stream: No such file or directory in /home/content/e/l/v/mydatabasename/html/wp-settings.php on line 84
Warning: main(/home/content/e/l/v/mydatabasename/html/wp-content/advanced-cache.php): failed to open stream: No such file or directory in /home/content/e/l/v/mydatabasename/html/wp-settings.php on line 84
Fatal error: main(): Failed opening required ‘/home/content/e/l/v/mydatabasename/html/wp-content/advanced-cache.php’ (include_path=’.:/usr/local/lib/php’) in /home/content/e/l/v/mydatabasename/html/wp-settings.php on line 84