Including the number of hashes (even if zero) is now required in GetArbitraryDataFileListMessage, to allow for additional fields. Enough peers should have updated by now for this to be ok.

src/main/java/org/qortal/network/message/GetArbitraryDataFileListMessage.java

@@ -99,6 +99,9 @@ public class GetArbitraryDataFileListMessage extends Message {
 					bytes.write(hash);
 				}
 			}
+			else {
+				bytes.write(Ints.toByteArray(0));
+			}
 
 			if (this.requestingPeer != null) {
 				Serialization.serializeSizedStringV2(bytes, this.requestingPeer);