FullError: FullError: database or disk is full even though there´s plenty of space?

[TheRookie]

I´ve just installed Calibre on a Windows 8.1 laptop and pointed it to the library stored on a NAS, when adding books i receive the following message

calibre, version 1.36.0
WARNING: Failed to read metadata: Failed to read metadata from the following:
<filename>.epub
Traceback (most recent call last):
  File "site-packages\calibre\gui2\add.py", line 165, in start
  File "site-packages\calibre\gui2\add.py", line 249, in add
  File "site-packages\calibre\db\legacy.py", line 211, in create_book_entry
  File "site-packages\calibre\db\cache.py", line 57, in call_func_with_lock
  File "site-packages\calibre\db\cache.py", line 1390, in create_book_entry
  File "site-packages\calibre\db\cache.py", line 1158, in set_metadata
  File "site-packages\calibre\db\cache.py", line 1145, in set_field
  File "site-packages\calibre\db\cache.py", line 963, in set_field
  File "site-packages\calibre\db\write.py", line 513, in set_books
  File "site-packages\calibre\db\write.py", line 375, in many_many
  File "site-packages\calibre\db\write.py", line 243, in get_db_id
  File "site-packages\calibre\db\backend.py", line 792, in execute
  File "c:\cygwin\home\kovid\sw\build\apsw-3.7.17-r1\src\cursor.c", line 231, in resetcursor
FullError: FullError: database or disk is full

Even though there is still 111Gb of free space left.

running calibre in debug mode yields the following

calibre Debug log
calibre 1.36  isfrozen: True is64bit: False
Windows-8-6.2.9200 Windows ('32bit', 'WindowsPE')
32bit process running on 64bit windows
('Windows', '8', '6.2.9200')
Python 2.7.5
Windows: ('8', '6.2.9200', '', 'Multiprocessor Free')
Starting up...
Started up in 48.10 seconds with 107 books
Worker Launch took: 1.62400007248
Job: 1 Read metadata (0 of 1) finished
Read metadata (0 of 1)

Added <filename>.epub to db in: 0.495000123978 seconds
Traceback (most recent call last):
  File "site-packages\calibre\db\backend.py", line 137, in write_serialized
IOError: [Errno 28] No space left on device

When i add the same ePub from my Mac, it gets added without any errors.

[kovidgoyal]

http://manual.calibre-ebook.com/faq....rked-drive-nas