# Re: hier\_blocks2 error

**URL:** <https://www.ruby-forum.com/t/re-hier-blocks2-error/243038>\
**Category:** GNU Radio\
**Created:** [August 17, 2015, 12:19pm UTC](https://www.ruby-forum.com/t/re-hier-blocks2-error/243038 "2015-08-17T12:19:30Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Sadaf\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@Sadaf\_N](https://www.ruby-forum.com/u/Sadaf_N)\
**Post date:** [August 17, 2015, 12:19pm UTC](https://www.ruby-forum.com/t/re-hier-blocks2-error/243038/1 "2015-08-17T12:19:30Z")

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> > AttributeError: ‘hier\_block2\_sptr’ object has no attribute ‘\_hb’  
> > marked protected they should not be accessed from outside the wrapper  
> > directly (I remember some WXGUI code did that, but that has been fixed).  
> > In the gnuradio tree I can’t seem to find anything like this.
> 
> Can you check and see from where this Exception is raised from?
> 
> Sebastian

The issue was in my python code that I derived from packet.py file. I  
was  
using this with 3.6.3

gr.io\_signature(1, 1,  
packet\_source.\_hb.output\_signature().sizeof\_stream\_item(0)) # Output  
signature)

I replaced it with

gr.io\_signature(1, 1,  
packet\_source.output\_signature().sizeof\_stream\_item(0)) # Output  
signature)

GRC flowgraph is working fine.

Thanks,  
Bob