python - AttributeError: 'NoneType' object has no attribute 'endswith' -

i working on python script updates web page. running main script generates error:

<res status='-1'><error message="'nonetype' object has no attribute 'endswith'"><![cdata[ traceback (most recent call last):   file "/path/to/file/ws_config.py", line xxxx, in run     tests = testlist().tests   file "/path/to/file/ws_config.py", line xxxx, in __init__     updatetestgroup(none),   file "/path/to/file/ws_config.py", line xxxx, in __init__     test = ct.curltest(settings),   file "/path/to/file/config_tests.py", line xxxx, in __init__     self.params.path = os.path.join('/', os.path.join(params.dir, params.file))   file "/usr/lib/python2.6/posixpath.py", line 67, in join     elif path == '' or path.endswith('/'): attributeerror: 'nonetype' object has no attribute 'endswith' 

i cannot past code because long. trying understand error lays or part of code triggering attributeerror. can please me???

the path in elif none , none == '' returns false remain executed. , backwards, params.dir none. need check code params.dir generated see how none come.