Had the same issue, was able to load nextcloud with php7.0, and it broke when switching to 7.1 and 7.2; it was an opcache issue.
I suggest you remove the lines relating to Redis and memcache from your config:
"memcache.local": "\\OC\\Memcache\\Redis",
"memcache.distributed": "\\OC\\Memcache\\Redis",
"memcache.locking": "\\OC\\Memcache\\Redis",
And follow the APCu path adding:
‘memcache.local’ => ‘\OC\Memcache\APCu’,
to the config.php