Can not open any of the previously created dashboards / charts

Can not open any of the previously created dashboards / charts

Any attempt to access previously created dashboards or even stand alone charts results in Alert Message:

" Sorry, an unexpected error occurred when performing this operation. The error has been logged and will be looked into.

It would be of great help if you could provide us with additional information using the ''Feedback'' link at the top of this page."

Tried to create a new chart - the same result.

Access to Tables appears to be unaffected.