# Error with gr\_modtool makexml howto\_detect\_ff

**URL:** <https://www.ruby-forum.com/t/error-with-gr-modtool-makexml-howto-detect-ff/242797>\
**Category:** GNU Radio\
**Created:** [July 28, 2015, 11:08am UTC](https://www.ruby-forum.com/t/error-with-gr-modtool-makexml-howto-detect-ff/242797 "2015-07-28T11:08:28Z")\
**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:** [July 28, 2015, 11:08am UTC](https://www.ruby-forum.com/t/error-with-gr-modtool-makexml-howto-detect-ff/242797/1 "2015-07-28T11:08:28Z")

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I am working to make a detector block in gnuradio 3.6.5.1 using gr-how  
“out-of-tree module”. I am stuck with an error during " gr\_modtool  
makexml howto\_detect\_ff " command.

GNU Radio module name identified: howto  
Warning: This is an experimental feature. Don’t expect any magic.  
Searching for matching files in lib/:  
Making GRC bindings for lib/howto\_detect\_ff\_impl.cc…  
Traceback (most recent call last):  
File “/usr/local/bin/gr\_modtool”, line 41, in   
main()  
File “/usr/local/bin/gr\_modtool”, line 37, in main  
modtool.run()  
File  
“/usr/local/lib/python2.7/dist-packages/gnuradio/modtool/modtool\_makexml.py”,  
line 66, in run  
(params, iosig, blockname) = self.\_parse\_cc\_h(f)  
File  
“/usr/local/lib/python2.7/dist-packages/gnuradio/modtool/modtool\_makexml.py”,  
line 157, in \_parse\_cc\_h  
return (parser.read\_params(), parser.read\_io\_signature(), blockname)  
File  
“/usr/local/lib/python2.7/dist-packages/gnuradio/modtool/parser\_cc\_block.py”,  
line 214, in read\_params  
params\_list = \_scan\_param\_list(make\_match.end(0))  
AttributeError: ‘NoneType’ object has no attribute ‘end’

Thanks in advance,  
CHAABANE