On the settings pages during upgrade and then on my site's home page I'm getting the following displayed.

Sibling File download not found

line 996 of /lib/adminlib.php: call to debugging()
line 216 of /admin/settings/plugins.php: call to admin_category->add()
line 6355 of /lib/adminlib.php: call to require()
line 6242 of /lib/adminlib.php: call to admin_get_root()
line 14 of /admin/upgradesettings.php: call to admin_externalpage_setup()

Sibling File download not found

line 996 of /lib/adminlib.php: call to debugging()
line 216 of /admin/settings/plugins.php: call to admin_category->add()
line 6355 of /lib/adminlib.php: call to require()
line 17 of /admin/upgradesettings.php: call to admin_get_root()

Sibling File download not found

line 996 of /lib/adminlib.php: call to debugging()
line 216 of /admin/settings/plugins.php: call to admin_category->add()
line 6355 of /lib/adminlib.php: call to require()
line 6454 of /lib/adminlib.php: call to admin_get_root()
line 21 of /admin/upgradesettings.php: call to admin_write_settings()

Sibling File download not found

line 996 of /lib/adminlib.php: call to debugging()
line 216 of /admin/settings/plugins.php: call to admin_category->add()
line 6355 of /lib/adminlib.php: call to require()
line 22 of /admin/upgradesettings.php: call to admin_get_root()