Recently, we encountered a very misleading error from SharePoint Online / Office 365 which took a long time to figure out. This blog explains the error and the underlying reason for the error. The wording of the error, “Additions to this Web site have been blocked,” did not accurately reflect the reason behind the error, making it very confusing. This blog will save you some time if you get the same error in your SharePoint Online / Office 365 site.

We have a document library in Office 365 / SharePoint Online. It includes certain columns as the metadata. This library crossed the threshold of 5,000, and since this threshold limit is a hard value and cannot be changed in SharePoint Online, we had to introduce two new Managed Metadata columns in the document library to enable the Managed navigation in the document library. The values in the Managed Metadata columns had to be populated from the existing columns in the document library, which were choice columns and not Managed Metadata columns.

A custom code using the Microsoft Client Side Object Model (CSOM) was developed to update the values from the non- Managed Metadata columns to the Managed Metadata columns. The application ran successfully for 10,000 items, and then suddenly it stopped, throwing the error, “Additions to this Web site have been blocked.” Our first thought was that we must have crossed some threshold of making the changes to the document library within a time window. However, we validated the site collection Storage Quota, Server Resources Quota, Storage Used, and the Custom Script setting which controls the running of the custom script of self-service created sites or on personal sites, and everything seemed to be in order. So, a support ticket was opened with Microsoft support. Microsoft validated that the site was alive, and that there was nothing in the Office 365 environment which would issue this kind of error. In addition, we were told that they do not have any expertise in reviewing the custom CSOM code.

In the end, we just looked at the exact list item which was causing the custom application to crash. This particular list item was checked out to a user and, while updating the column values in this list item, the Office 365 was throwing the error, “Additions to this Web site have been blocked.” Once I checked in the list item, the same code worked perfectly.

I hope this blog post saves you some time in troubleshooting this error.

To find out more how RSM can assist you with your SharePoint needs, contact RSM’s technology consulting professionals at 800.274.3978 or email us.