Looks like this bit means that no objects were found in the result of your LDAP search:
LDAP search returned non-array result: 1 [auth.php:211]
I also notice that the function call in lib/plugins/authldap/auth.ldap which returns the non-array result has a leading @, which
suppresses PHP errors:
$result = @ldap_get_entries($this->con, $sr);
If you're comfortable hacking it out, maybe try removing the @ to see if you get any useful feedback from PHP... but this is not exactly a recommendation, but rather just something I'd try myself in a test environment.
Also, I wonder if there might not be a bug in the line which prints the error I cite above. PHP print() always returns 1, you might try changing this line:
$this->_debug('LDAP search returned non-array result: '.htmlspecialchars(print($result)), -1, __LINE__, __FILE__);
to this:
$this->_debug('LDAP search returned non-array result: '.htmlspecialchars(print_r($result,TRUE)), -1, __LINE__, __FILE__);
However, before we get too deeply into that, is your LDAP served by ActiveDirectory? If so, have you considered using the authad plugin instead?
authad plugin documentation wrote
While Active Directory authentication can be set up with the bundled authLDAP plugin, it should be easier to do with this dedicated AD auth plugin.
Also, what environment does your wiki run on? Linux/Windows?
Are you able to pull LDAP directory information from the command line using something like ldapsearch?