Hi all,

Some of you, those who have custom lists in your SharePoint sites, may eventually face this issue. The cause, and the solution, is pretty simple though is particularly hidden inside your SharePoint settings.

SharePoint Server 2010 introduced a new feature: Resource Throttling. It is intended to monitor and optimize resources for large lists and web applications. More information here.

In these Resource Throttling settings there is a particular value that affects your custom lists, in particular, those which have look up columns. The List View Lookup Threshold value determines how many lookups can be displayed in a single list view. The default value is 6, or 8, and usually works perfectly fine for almost everybody.

What happens if you have, let's say, 9 lookup columns in your custom list? You see this 500 error. If you enable the Technical Log in SharePlus (iOS) or review your server's logs, you will see in them that the error details state: "The query cannot be completed because the number of lookup columns it contains exceeds the lookup column threshold". That's right, your list has "too many" lookups.

The solution is simple. You need to change the List View Lookup Threshold value to something like 20 (I know, it doesn't make sense) and, by trial and error, start decreasing the value until you hit the right one that is low enough to work. The reason I say 20 and not 9 is because in most cases I've dealt with users had 7 to 9 lookup fields and changing the threshold to 7 or 9 wouldn't work (the user with 9 lookups had this working with a threshold of 21, 20 wouldn't be enough).

Visit this Microsoft article for more information on how to configure this value.

I hope this is helpfull for you all.

Best regards,