[jbrobrown]

I have a number of books I have scanned into MS Word format. I save them as HTML and convert to MOBI for use on my Kindle. With Calibre version 7.27 I have started getting errors on about one book in five. These are books that converted OK on earlier versions. Problem still exists on version 7.31 The error mesage is:
Python function terminated unexpectedly
'NoneType' object is not iterable (Error Code: 1)
Traceback (most recent call last):
File "site.py", line 103, in main
File "site.py", line 85, in run_entry_point
File "site-packages\calibre\utils\ipc\worker.py", line 107, in main
File "site-packages\calibre\gui2\convert\gui_conversion.py", line 24, in gui_convert
File "site-packages\calibre\ebooks\conversion\plumber.py", line 948, in run
File "site-packages\calibre\ebooks\mobi\output.py", line 174, in convert
File "site-packages\calibre\ebooks\mobi\mobiml.py", line 102, in __call__
File "site-packages\calibre\ebooks\mobi\mobiml.py", line 125, in mobimlize_spine
File "site-packages\calibre\ebooks\mobi\mobiml.py", line 443, in mobimlize_elem
File "site-packages\calibre\ebooks\mobi\mobiml.py", line 443, in mobimlize_elem
File "site-packages\calibre\ebooks\mobi\mobiml.py", line 443, in mobimlize_elem
File "site-packages\calibre\ebooks\mobi\mobiml.py", line 436, in mobimlize_elem
TypeError: 'NoneType' object is not iterable

I suspect but don't know that the problem may be empty text boxes. These are sometimes hard to see. Any ideas , Thanks