The explanation behind this (because Fabio has said where to look) is that most charts, gadgets and reports run off a saved filter. The saved filter gives them a list of issues that currently match its question and they then read that list to extract the data they need to draw up their reporting.
You get this error with almost every gadget or report when the filter has been broken. Jira tries to stop you saving broken filters, but it can't stop one breaking if you change the structure of what it is looking at. And that's what I suspect has happened here.
Simple example - if you've got a filter that says "Project = XYZ and instruction-text is not empty", and you delete the field called instruction-text, you will break the filter, because there's no field for it to look at any more.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.