I’m running Nextcloud v26 as a container on an Unraid server together with Redis.
Parts of the config.php looks like this:

$CONFIG = array (
‘memcache.locking’ => ‘\OC\Memcache\Redis’,
‘memcache.local’ => ‘\OC\Memcache\Redis’,
‘redis’ =>
array (
‘host’ => ‘redis’,
‘port’ => 6379,
‘password’ => ‘nopey’,

I try to run this command from inside the container
occ preview:generate-all

But after a while it throws the error:
PHP Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to allocate 77824 bytes) in /config/www/nextcloud/lib/private/legacy/OC_Image.php on line 533

Not sure where to start tbh.
Some other threads have mentioned setting apc.enable_cli=1, but it seems to been done, inside the file /etc/php81/conf.d/apcu.ini

I also get errors every time I try to upgrade Nextcloud. Times out every time. Maybe it’s related?

EDIT:
Tried to change
‘memcache.local’ => ‘\OC\Memcache\APCu’,

But unfortunately, no difference

Your system is low on memory. 512 MB is the minimum requirement, if you have installed too many apps, that can easily trigger such a problem. Also to consider, if you are at the minimum requirement, you need to adjust all your services to be as efficient as possible (database, webserver, …), that can be tricky since the best configuration can depend on the use case.

Generating thumbnails takes up some resources: