Seems you're not the first to
run into this issue:
adispi wrotei cannot find a solution on the web without changing the code of the dokuwiki.
the issues that this is causing me is that the wiki does not get a full reply from the AD and there for finds part of groups and usually they are incomplete, so when i set permission for a group, not all the users can access the wiki.
Unfortunately, no mention of what code change
adispi may have made to work around the issue.
I am not an expert in this area, but If I had to guess, this
StackOverflow discussion which might be relevant. If I had this issue, and I had a development environment to test in, I might try overriding the sizelimit parameter in the line referenced in the warning, but it'd be very much a guess/hack. I'm not necessarily recommending this.
From authAD plugin page:
Due to missing support for paged queries in PHP's LDAP extension, plugins that try to get all users from the auth backend will fail if you use authAD plugin and have more than 1000 objects in Active Directory. One example is the IssueTracker plugin.
No doubt someone else will be able to provide better information than me. If you're lucky, authAD author
andi may be able to point you at the answer.