Problem with Kobo Glo

When I connect my Kobo Glo, and try to read the ebooks on the device I get an error popup with this error

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calibre, version 0.9.10
ERROR: Unhandled exception: <b>TypeError</b>:sequence item 0: expected string, NoneType found

Traceback (most recent call last):
File "site-packages\calibre\gui2\library\models.py", line 1394, in data
TypeError: sequence item 0: expected string, NoneType found
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Apparently there is something missing.
Oh yes, it only reads up to 9 ebooks, always the same ones, and then stops and even if I push the OK button, it stays here, same popup.

Before opening a ticket, I would like to understand if it is a known problem (maybe due to some mistake in reading an ebook ?) and if I am doing something wrong, as I understand that the driver is quite stable.

As an additional info, I only have Kobo ebooks on the device, until now. As a second effect, in fact, I cannot transfer the ebooks from Calibre. I get this message :

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calibre, version 0.9.10
ERROR: Error: Error communicating with device

'NoneType' object has no attribute 'strip'

Traceback (most recent call last):
File "site-packages\calibre\gui2\device.py", line 85, in run
File "site-packages\calibre\gui2\device.py", line 500, in _sync_booklists
File "site-packages\calibre\devices\kobo\driver.py", line 874, in sync_booklists
File "site-packages\calibre\devices\kobo\driver.py", line 1889, in update_device_database_collections
File "site-packages\calibre\devices\kobo\books.py", line 202, in get_collections
AttributeError: 'NoneType' object has no attribute 'strip'

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Thanks in advance

Bruno

Bruno