LDAP Configuration "Counting entries. This may take a while" never ends

I modified the file /opt/zammad/Gemfile according to your instructions, but when running bundle install I get the following error:

$ /opt/zammad/bin/bundle install
/usr/lib/ruby/2.1.0/rubygems.rb:235:in `bin_path': can't find gem bundler (>= 0) (Gem::GemNotFoundException)
	from /opt/zammad/bin/bundle:3:in `<main>'
$

The same error appears when running /opt/zammad/vendor/bundle/ruby/2.4.0/bin/bundle install. What else could I try? Sorry, Ruby is completely foreign territory for me :wink:

I have no possibility to restart the LDAP server.