I have seen the following error a number of times now and it can cause all sorts of problems with lists and libraries, especially with custom code that calls the SharePoint web services.
This view cannot be displayed because the number of lookup and workflow status columns it contains exceeds the threshold (8) enforced by the administrator
The problem occurs because the number of managed metadata fields on a library exceeds the number permitted in the SharePoint environment configuration. When this error occurs it can cause the SharePoint web services can refuse to return documents.
Fortunately the limit can easily be increased with the following steps:
- Go to Central Admin > Manage Web Applications.
- Select required Web Application > Click General Settings & select Resource throttling
- Locate the List View Lookup Threshold property and increase as required.
Everything should now work as expected.