Excel Services: I Ticked "Trust Children," Why Doesn't It Work?

At work we have a BI system based on Microsoft technologies: SharePoint 2007/Excel Services as the front end and SQL Analysis Services as the back end.

A couple of colleges did most of the setup for the SharePoint server, including Excel Services. Based on their experience, they have always advised others that the "Trust Children" setting in Trusted File Locations did not work. Therefore, we have always been creating an individual entry for each document library we want to use with Excel Services.

Earlier this year we were setting up a QA environment for the BI system. I had the chance to test the Excel Services settings for myself. What I found was that the setting to "Trust Children" does work, it just doesn't always work right away. Sometimes it might take up to 30 seconds or so before it would take effect.

I guess this short delay explains why they thought the setting didn't work. But at least now we no longer need to create all those entries in Trusted File Locations.

Note: for security best practice, you should still consider carefully whether to enable this setting based on your deployment scenario. Refer to the guidelines in this article.