I was using a code similar to this (with #include wstring.h) ;
... String myString : String(20); ... Wire.send(myString);
but from arduino 20 this doesn't work anymore. The Wtring is now core of arduino but the same code creates now an error I con't find a way to solve :
no matching function for call to 'TwoWire::send(String&)'
Thanks for advices