If you work with large lists there is a good chance you might have run into this threshold error message in Office 365.
A Lookup column in a list view will cause a join with another table in the back-end. More lookup columns implies more joins in the back-end resulting in performance hit. That is the reason why Microsoft set a limit of number of lookup columns you can display in a view. In SharePoint online Office 365, at the time of this writing it is set to 12 by default.
In some cases like mine – you may see this error even without having a single traditional lookup column in your list or view. Reason being, SharePoint considers some other column types as lookup columns.
Column data types which are counted against SharePoint’s list view lookup and workflow column threshold:
- Traditional lookup column
- Single-value managed metadata column
- Multi-value managed metadata column
- People & group column
- Multi-value people & group column
If you get this error try to reduce the number of lookup columns which are displayed in the view.