Kindle "get list of books on device" failing

[Phssthpok]

Every time I connect my Kindle, I get the following error at the end of the "get list of books from device":

calibre, version 3.24.2
ERROR: Error: Error communicating with device

[Errno 22] invalid mode ('wbN') or filename: u'E:\\metadata.calibre'

Traceback (most recent call last):
File "site-packages\calibre\gui2\device.py", line 87, in run
File "site-packages\calibre\gui2\device.py", line 510, in _books
File "site-packages\calibre\devices\kindle\driver.py", line 409, in books
File "site-packages\calibre\devices\usbms\driver.py", line 296, in books
File "site-packages\calibre\devices\usbms\driver.py", line 448, in sync_booklists
File "site-packages\calibre\devices\usbms\driver.py", line 445, in write_prefix
File "site-packages\calibre\startup.py", line 116, in local_open
IOError: [Errno 22] invalid mode ('wbN') or filename: u'E:\\metadata.calibre'

Any idea what might be causing this, and what I should do about it?

[kovidgoyal]

Probably too many entries in the root of E: drive, dlet some or move them into a sub-folder. FAT filesystems such as the kindle uses have very low limit on the number of items in the root directory.

[Phssthpok]

Originally Posted by kovidgoyal

Probably too many entries in the root of E: drive, dlet some or move them into a sub-folder. FAT filesystems such as the kindle uses have very low limit on the number of items in the root directory.

Nope. The root directory has only four subdirectories (and all the books are in the "documents" subdir) and two Calibre metadata files.

Closer inspection showed that metadata.calibre was 0 bytes in size, and when I tried to delete it I got a "corrupt file" error: "The file or directory \metadata.calibre is corrupt and unreadable. Please run the Chkdsk utility". So, in fear and trepidation I did so. Some tangled block chains were untangled and it all started working properly again.

Not sure why this should have happened, though. The Kindle is a new one (about a month old). The only thing I can think of is a dodgy USB connection, but even then...

Oh well. Problem solved, anyway.