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): 15.0.2
Operating system and version (eg, Ubuntu 17.04): FreeNAS-11.2-RELEASE-U1
Apache or nginx version (eg, Apache 2.4.25): nginx/1.14.2
PHP version (eg, 7.1): 7.1.26
The issue you are facing: I cannot connect to my AD with NextCloud. It says:
Connection to LDAP server could not be established
The Base DN appears to be wrong
Is this the first time you’ve seen this error? (Y/N): Y
Steps to replicate it:
- Try to connect to AD
- That’s it
The output of your Nextcloud log in Admin > Logging:
Configuration Error (prefix s01): login filter does not contain %uid place holder.
Configuration Error (prefix s01): No LDAP Login Filter given!
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
'ldapIgnoreNamingRules' => false,
'ldapProviderFactory' => 'OCA\\User_LDAP\\LDAPProviderFactory',
The output of your Apache/nginx/system log in /var/log/____:
no significant information