After updating server - Multiple errors

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Nextcloud version (eg, 20.0.5): 24.0.1
Operating system and version (eg, Ubuntu 20.04): Ubuntu 20.04.4 LTS
Apache or nginx version (eg, Apache 2.4.25): Apache 2.4.41
PHP version (eg, 7.4): 7.4

The issue you are facing:
Multiple errors occurring on the Security and setup warnings
PHP Configuration option output_buffering must be disabled - I’ve checked the php.ini buffer setting it is set to disabled
your data directory and files are probably accessible from the internet. The .htaccess file is not working - Not sure what this requires to be fixed I’ve tried to find solutions and don’t exactly understand the solution.

your web server is not properly set up to resolve "/.well-known/webfinger, nodeinfo, caldav, carddav etc - I read the documentation on this and have updated the file to have these headers or modules and it doesn’t seem to make the error go away not sure what I missed

no memory cache has been configured. to enhance performance please configure memcache.
I don’t understand this https://docs.nextcloud.com/server/latest/admin_manual/configuration_server/caching_configuration.html and what the actual fix is as its explaining the different ways of doing memcache and distributed cache

Is this the first time you’ve seen this error? (Y/N): Yes - all these errors were not displaying on the previous version of nextcloud.

Steps to replicate it:

  1. restarted server
  2. restarted apache service

The output of your Nextcloud log in Admin > Logging:

How do i get a report of the admin > logging to paste here ?

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

there is no config.php file in the /var/www/nextcloud folder 

not sure about other log files and requirements as I tried to search for the locations provided in this topic window but was unable to locate them.

the config.php is at /var/www/nextcloud/config/config.php

also examine config.sample.php there