What causes the 'DB Error: unknown error' after adding custom fields to a report in CiviCRM? I have one particular set of custom fields made up of plain text fields and rich text fields. But if I try to add any of them to a report for display, the following error is returned:


  DB Error: unknown error 


I don't have this problem with other similar custom field sets, just this one. Is this something anyone has experience before? What's the cause of it?
After turning on the debugging tool,it appears the field label was changed at some point and now cannot be referenced through reporting because the database is expecting the old field label and set name of the database cell to be referenced. It doesn't affect exporting the data though. If you have no access to the actual server then a solution is to create a new field and export and import all the data from the errant field to the new field, as far as I understand.