For the benefit of the discussion and of the general public:
Ref NC 16 Docs » Nextcloud configuration » Memory caching
Nextcloud supports multiple memory caching backends, so you can choose the type of memcache that best fits your needs. The supported caching backends are:
APCu, APCu 4.0.6 and up required.
A local cache for systems.Redis, PHP module 2.2.6 and up required.
For local and distributed caching as well as transactional file locking.Memcached
For distributed caching.Memcaches must be explicitly configured in Nextcloud by installing and enabling your desired cache, and then adding the appropriate entry to
config.php
[…]
Note: […] Nextcloud supports only the memcached PHP module.
Hope this helps.