Each data element must implement a unique 'id' property

Enonic version: 7.7.2
Content Studio version: 3.3.4
OS: Ubuntu 16.04.7 LTS

I’m experiencing the exact same issue as the one reported at Custom Selector error unique 'id' property. Since it’s a quite old thread I’ve decided to open a new one. It’s the exact same issue with the error message showing up in the Custom Selector dropdown, but now in Content Studio 3.3.4 / XP 7.7.2.

Logs have been added to the service used in the Custom Selector and the data structure being returned in the body object looks all good. Considering it’s a solution that’s been running stable for a few years now and we’ve only been experiencing such error recently I wonder if there could be any relation to the version of Content Sutdio (3.3.4).

The error message will only show up sometimes, with no specific pattern. No error/exception is actually issued in the output logs.


This is a major issue for one of our customers too.

I’ve been intending to investigate this more, and post about it here, but you beat me to it.


Yes, this is a very annoying bug that I have seen in several installations. I hope you can find a fix.


@diegopr @tom @hilde check that you have correctly implemented paging in your custom selector’s service and verify that custom selector sends correct paging parameters (start and count) when fetching data.

Basically, if your page size is set to 10 items, then first request should be “?count=10”, second “?start=10&count=10” and so on, as you scroll inside the dropdown. If you are instantly getting the error, check what parameters you have on the first (and only) request sent to the custom selector service. If count parameter is missing or there are more than one identical requests sent, then there’s a problem with implementation.