Unable to load content because "Content reader could not be found" Exception


I’m trying to port a XNA based engine on Monogame and i face an issue during content loading.

I’ve got a CommonEvent which contains an array of EventCommand.

class CommonEvent

public EventCommand[] list;

EventCommand contains short typed variables.
All CommonEvent are serialized in an XML then processed as an XNB.
The pipeline sucessfully build the XNB.

But when i try to load the xnb, it fails.
Reason :
Exception is : Could not load Data/commonevents asset as a non-content file!
Inner Exception is : Content reader could not be found for System.Int16[] type.

I first thought it was because EventCommand contains short typed variables, then i changed them to int but same problem at load except its a Content reader could not be found for System.Int32[] type.

I searched a similar post and found : https://github.com/mono/MonoGame/issues/4032
But no solution given.

Is there a workaround to fix it ?

I don’t use the latest git source but the last version of monogame ( i.e : 3.4 ).

Thanks in advance for your support.