SharePoint 2013 and Large Lookup Lists

SharePoint 2013 and an Unexpected Cost of Large Lookup Lists

SharePoint 2013 can handle very large lists (given a very restrictive set of requirements). There is however one error that slipped through the cracks from the Microsoft SharePoint development team. When the total number of items in a list exceed 20,000 items (mileage may vary); you may lose the ability to use the list as a Lookup Column while maintaining the ability to edit the list item via the default edit form.

Under the hood

A lookup component has two pieces: SharePoint ID and the display column (selected when created the column).

When the sum of this data across the entire list exceeds ~2 MB; users can no longer edit the list items via edit form.

Solution coming in future updates.