this error gives by java script attach to form onsave , you need to open form customisation. open one account, on top customize tab, click form then go to form properties . there you can see form libraries, and event handlers.
under event handlers select Form and Event onsave
then you can see the javascript library double click to open it and edit.
this error gives if you add a field name wrong in the script . so you need to cross check field names in java script spell correctly or not
hope this will help you
