Class InvalidOperation

              object --+                    
                       |                    
exceptions.BaseException --+                
                           |                
        exceptions.Exception --+            
                               |            
        exceptions.StandardError --+        
                                   |        
          exceptions.ArithmeticError --+    
                                       |    
                        DecimalException --+
                                           |
                                          InvalidOperation

Known Subclasses:

• ConversionSyntax
• , DivisionImpossible
• , DivisionUndefined
• , InvalidContext

An invalid operation was performed.

Various bad things cause this:

Something creates a signaling NaN
-INF + INF
 0 * (+-)INF
 (+-)INF / (+-)INF
x % 0
(+-)INF % x
x._rescale( non-integer )
sqrt(-x) , x > 0
0 ** 0
x ** (non-integer)
x ** (+-)INF
An operand is invalid