As others here, I'm facing the issue that LDAP authentication doesn't work with the current versions of PluggableAuth and LDAPAuthencation2, giving the following error message:
The supplied credentials could not be authenticated.
But I realized that rolling back to version REL1_35 for PluggableAuth actually works fine on MediaWiki 1.39.
Note that other extensions should not be rolled back. In particular, LDAPProvider must be updated to REL1_39, or you'll face another error while logging in.
For LDAPAuthentication2 and LDAPUserInfo, either version seems to be working fine, so it's probably best to use the newer REL1_39.