Hi I also have the same problem.
Allowed memory size of 536870912 bytes exhausted (tried to allocate 20480 bytes) at /config/www/nextcloud/3rdparty/doctrine/dbal/lib/Doctrine/DBAL/Driver/PDOStatement.php#158
I already tried to fix it, I manually allocated the 2048 M but it did not change anything.
I have found another Error, I don't know if it depends on the other one
Sabre\DAV\Exception: An exception occurred while executing 'UPDATE `oc_file_locks` SET `lock` = `lock` + 1, `ttl` = ? WHERE `key` = ? AND `lock` >= 0' with params [1595517022, "files\/4928438206cae1cd38d56633a8b93eb1"]: SQLSTATE[40001]: Serialization failure: 1213 Deadlock found when trying to get lock; try restarting transaction
/config/www/nextcloud/apps/dav/lib/Connector/Sabre/File.php - line 418:
OCA\DAV\Connector\Sabre\File->convertToSabreException(Doctrine\DBA ... {})
/config/www/nextcloud/3rdparty/sabre/dav/lib/DAV/CorePlugin.php - line 85:
OCA\DAV\Connector\Sabre\File->get()
<<closure>>
Sabre\DAV\CorePlugin->httpGet(Sabre\HTTP\R ... "}, Sabre\HTTP\Response {})
/config/www/nextcloud/3rdparty/sabre/event/lib/EventEmitterTrait.php - line 105:
call_user_func_array([ Sabre\DAV\ ... "], [ Sabre\HTTP ... }])
/config/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php - line 479:
Sabre\Event\EventEmitter->emit("method:GET", [ Sabre\HTTP ... }])
/config/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php - line 254:
Sabre\DAV\Server->invokeMethod(Sabre\HTTP\R ... "}, Sabre\HTTP\Response {})
/config/www/nextcloud/apps/dav/lib/Server.php - line 319:
Sabre\DAV\Server->exec()
/config/www/nextcloud/apps/dav/appinfo/v2/remote.php - line 35:
OCA\DAV\Server->exec()
/config/www/nextcloud/remote.php - line 165:
require_once("/config/www ... p")
When I try to upload Files to my server it is very slow since the problem occurred.
It is since I updated to 18.0.7. Security & setup warning are all fine, nothing wrong.