Support intro
Sorry to hear you’re facing problems 
help.nextcloud.com is for home/non-enterprise users. If you’re running a business, paid support can be accessed via portal.nextcloud.com where we can ensure your business keeps running smoothly.
In order to help you as quickly as possible, before clicking Create Topic please provide as much of the below as you can. Feel free to use a pastebin service for logs, otherwise either indent short log examples with four spaces:
example
Or for longer, use three backticks above and below the code snippet:
longer
example
here
Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can 
Nextcloud version (eg, 12.0.2): 18.0.1
Operating system and version (eg, Ubuntu 17.04): Debian Stretch
Apache or nginx version (eg, Apache 2.4.25):
PHP version (eg, 7.1):
The issue you are facing:
I don’t have an option in the three dots menu of a file to lock the file for editing. My understanding is that is where it should reside in V18? Wondering if I have something configured wrong?
Is this the first time you’ve seen this error? (Y/N): N
The output of your Nextcloud log in Admin > Logging:
PASTE HERE
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
PASTE HERE
The output of your Apache/nginx/system log in /var/log/____:
PASTE HERE