get Null pointer exception in gt06

hi
i am using device like gt06 protocol .both device are same kind of protocol but when i run with gt06 at the 1st point it was run but now i get some exception NullPointerException like following kind :-

 (... < DefaultDataHandler:38 < BaseDataHandler:17 < ... < ExtendedObjectDecoder:27 < ...)

how can i solve this ? my hex code for this protocol is :

7878110108630145318846020100320000868a5d0d0a

Are you using official release downloaded from this website without any modifications? What version?

thank you anton for reply .
i used traccar version 3.5 but i modify code for datamanager not for protocol decoder .

and may be this exception call at that point
return position

Try latest official release. If it works there, you either need to upgrade or look for the issue in your code.

Thanks Ok.