A docuement from Amazon shows gibberish. Here's the technical log.

[luigi rovatti]

Here's the log during conversion, and during running Calibre in "debug mode".

Conversion log:

Converti libro 1 di 1 (The Mythology of Global Warming_ Climate Change Fiction vs. Scientific Facts)
DeDRM v7.2.1: Trying to decrypt _vcs9hiv.mobi
Using Library AlfCrypto DLL/DYLIB/SO
Using Library AlfCrypto DLL/DYLIB/SO
MobiDeDrm v1.0.
Copyright © 2008-2020 The Dark Reverser, Apprentice Harper et al.
Decrypting Mobipocket 4 ebook: THE MYTHOLOGY OF GLOBAL WARMING: Climate Change Fiction vs. Scientific Facts
Got DSN key from database default_key
Got DSN key from database default_key_2
Found 6 keys to try after 0.1 seconds
Crypto Type is: 0
This book is not encrypted.
Decryption succeeded after 0.1 seconds
DeDRM v7.2.1: Finished after 0.1 seconds
Conversion options changed from defaults:
  cover: 'C:\\Users\\luigi\\AppData\\Local\\Temp\\calibre_39l8twe2\\8osp7ugr.jpeg'
  verbose: 2
  read_metadata_from_opf: 'C:\\Users\\luigi\\AppData\\Local\\Temp\\calibre_39l8twe2\\tm3y7kp3.opf'
  output_profile: 'kindle_pw3'
Resolved conversion options
calibre version: 5.43.0
{'asciiize': False,
 'author_sort': None,
 'authors': None,
 'base_font_size': 0.0,
 'book_producer': None,
 'change_justification': 'original',
 'chapter': "//*[((name()='h1' or name()='h2') and re:test(., "
            "'\\s*((chapter|book|section|part)\\s+)|((prolog|prologue|epilogue)(\\s+|$))', "
            "'i')) or @class = 'chapter']",
 'chapter_mark': 'pagebreak',
 'comments': None,
 'cover': 'C:\\Users\\luigi\\AppData\\Local\\Temp\\calibre_39l8twe2\\8osp7ugr.jpeg',
 'debug_pipeline': None,
 'dehyphenate': True,
 'delete_blank_paragraphs': True,
 'disable_font_rescaling': False,
 'dont_compress': False,
 'duplicate_links_in_toc': False,
 'embed_all_fonts': False,
 'embed_font_family': None,
 'enable_heuristics': False,
 'expand_css': False,
 'extra_css': None,
 'extract_to': None,
 'filter_css': '',
 'fix_indents': True,
 'font_size_mapping': None,
 'format_scene_breaks': True,
 'html_unwrap_factor': 0.4,
 'input_encoding': None,
 'input_profile': <calibre.customize.profiles.InputProfile object at 0x000001CA31933490>,
 'insert_blank_line': False,
 'insert_blank_line_size': 0.5,
 'insert_metadata': False,
 'isbn': None,
 'italicize_common_cases': True,
 'keep_ligatures': False,
 'language': None,
 'level1_toc': None,
 'level2_toc': None,
 'level3_toc': None,
 'line_height': 0.0,
 'linearize_tables': False,
 'margin_bottom': 5.0,
 'margin_left': 5.0,
 'margin_right': 5.0,
 'margin_top': 5.0,
 'markup_chapter_headings': True,
 'max_toc_links': 50,
 'minimum_line_height': 120.0,
 'mobi_toc_at_start': False,
 'no_chapters_in_toc': False,
 'no_inline_navbars': False,
 'no_inline_toc': False,
 'output_profile': <calibre.customize.profiles.KindlePaperWhite3Output object at 0x000001CA31933AC0>,
 'page_breaks_before': "//*[name()='h1' or name()='h2']",
 'prefer_author_sort': False,
 'prefer_metadata_cover': False,
 'pretty_print': False,
 'pubdate': None,
 'publisher': None,
 'rating': None,
 'read_metadata_from_opf': 'C:\\Users\\luigi\\AppData\\Local\\Temp\\calibre_39l8twe2\\tm3y7kp3.opf',
 'remove_fake_margins': True,
 'remove_first_image': False,
 'remove_paragraph_spacing': False,
 'remove_paragraph_spacing_indent_size': 1.5,
 'renumber_headings': True,
 'replace_scene_breaks': '',
 'search_replace': '[]',
 'series': None,
 'series_index': None,
 'share_not_sync': False,
 'smarten_punctuation': False,
 'sr1_replace': None,
 'sr1_search': None,
 'sr2_replace': None,
 'sr2_search': None,
 'sr3_replace': None,
 'sr3_search': None,
 'start_reading_at': None,
 'subset_embedded_fonts': False,
 'tags': None,
 'timestamp': None,
 'title': None,
 'title_sort': None,
 'toc_filter': None,
 'toc_threshold': 6,
 'toc_title': None,
 'transform_css_rules': '[]',
 'transform_html_rules': '[]',
 'unsmarten_punctuation': False,
 'unwrap_lines': True,
 'use_auto_toc': False,
 'verbose': 2}
DeDRM v7.2.1: Trying to decrypt 3jw7ujv7.mobi
MobiDeDrm v1.0.
Copyright © 2008-2020 The Dark Reverser, Apprentice Harper et al.
Decrypting Mobipocket 4 ebook: THE MYTHOLOGY OF GLOBAL WARMING: Climate Change Fiction vs. Scientific Facts
Got DSN key from database default_key
Got DSN key from database default_key_2
Found 6 keys to try after 0.0 seconds
Crypto Type is: 0
This book is not encrypted.
Decryption succeeded after 0.0 seconds
DeDRM v7.2.1: Finished after 0.0 seconds
InputFormatPlugin: MOBI Input running
on C:\Users\luigi\AppData\Local\Temp\calibre_39l8twe2\0h7rp89h.mobi
Extracting text...
Adding anchors...
Extracting images...
Cleaning up HTML...
Parsing HTML...
Malformed markup, parsing using html5-parser
Converting style information to CSS...
Creating OPF...
Parsing all content...
Parsing styles.css ...
Parsing index.html ...
Initial parse failed, using more forgiving parsers
Parsing index.html as HTML
HTML 5 parsing failed, falling back to older parsers
Traceback (most recent call last):
  File "calibre\ebooks\oeb\parse_utils.py", line 211, in parse_html
  File "calibre\utils\xml_parse.py", line 26, in safe_xml_fromstring
  File "src/lxml/etree.pyx", line 3237, in lxml.etree.fromstring
  File "src/lxml/parser.pxi", line 1896, in lxml.etree._parseMemoryDocument
  File "src/lxml/parser.pxi", line 1777, in lxml.etree._parseDoc
  File "src/lxml/parser.pxi", line 1082, in lxml.etree._BaseParser._parseUnicodeDoc
  File "src/lxml/parser.pxi", line 615, in lxml.etree._ParserContext._handleParseResultDoc
  File "src/lxml/parser.pxi", line 725, in lxml.etree._handleParseResult
  File "src/lxml/parser.pxi", line 654, in lxml.etree._raiseParseError
  File "<string>", line 8
lxml.etree.XMLSyntaxError: Attribute _ redefined, line 8, column 1587

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "calibre\ebooks\oeb\parse_utils.py", line 218, in parse_html
  File "calibre\utils\xml_parse.py", line 26, in safe_xml_fromstring
  File "src/lxml/etree.pyx", line 3237, in lxml.etree.fromstring
  File "src/lxml/parser.pxi", line 1896, in lxml.etree._parseMemoryDocument
  File "src/lxml/parser.pxi", line 1777, in lxml.etree._parseDoc
  File "src/lxml/parser.pxi", line 1082, in lxml.etree._BaseParser._parseUnicodeDoc
  File "src/lxml/parser.pxi", line 615, in lxml.etree._ParserContext._handleParseResultDoc
  File "src/lxml/parser.pxi", line 725, in lxml.etree._handleParseResult
  File "src/lxml/parser.pxi", line 654, in lxml.etree._raiseParseError
  File "<string>", line 8
lxml.etree.XMLSyntaxError: Attribute _ redefined, line 8, column 1587

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "calibre\ebooks\oeb\parse_utils.py", line 224, in parse_html
  File "calibre\ebooks\oeb\parse_utils.py", line 105, in html5_parse
ValueError: HTML 5 parsing resulted in a tree with nesting depth > 100

Forcing index.html into XHTML namespace
Generating default TOC from spine...
Merging user specified metadata...
Detecting structure...
Auto generated TOC with 0 entries.
Flattening CSS and remapping font sizes...
Source base font size is 12.00000pt
Removing fake margins...
Cleaning up manifest...
Trimming unused files from manifest...
Trimming 'images/00002.jpg' from manifest
Trimming 'images/00001.jpg' from manifest
Creating AZW3 Output...
Serializing resources...
Splitting markup on page breaks and flow limits, if any...
Creating KF8 output
	Generating KF8 markup...
Tag fm______m5_ma__ml__m___ has no aid and a too large chunk size. Adding anyway.
	Compressing markup...
	Creating indices...
Document has no ToC, MOBI will have no NCX index
AZW3 output written to C:\Users\luigi\AppData\Local\Temp\calibre_39l8twe2\t18_oy6v.azw3

Debug mode log:

EpubMerge: DEBUG: 2022-06-01 23:18:54,025: calibre_plugins.epubmerge.epubmerge_plugin(155): macmenuhack file_path:C:\Users\luigi\AppData\Roaming\calibre\plugins\fanficfare_macmenuhack.txt
FFF: INFO: 2022-06-01 23:18:54,031: calibre_plugins.fanficfare_plugin.prefs(214): Using default settings
FFF: DEBUG: 2022-06-01 23:18:54,042: calibre_plugins.fanficfare_plugin.fff_plugin(218): Plugin FanFicFare macmenuhack file_path:C:\Users\luigi\AppData\Roaming\calibre\plugins\fanficfare_macmenuhack.txt
calibre Log di debug
calibre 5.43 [64bit]  embedded-python: True is64bit: True
Windows-10-10.0.22000 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.22000')
Python 3.8.5
Windows: ('10', '10.0.22000', '', 'Multiprocessor Free')
Interface language: it
Successfully initialized third party plugins: Gather KFX-ZIP (from KFX Input) (1, 49, 0) && DeDRM (7, 2, 1) && Package KFX (from KFX Input) (1, 49, 0) && EpubMerge (2, 13, 0) && EpubSplit (3, 3, 0) && FanFicFare (4, 13, 0) && KFX metadata reader (from KFX Input) (1, 49, 0) && KFX Input (1, 49, 0) && KindleUnpack - The Plugin (0, 83, 1)
calibre 5.43 [64bit]  embedded-python: True is64bit: True
Windows-10-10.0.22000 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.22000')
Python 3.8.5
Windows: ('10', '10.0.22000', '', 'Multiprocessor Free')
Interface language: it
Successfully initialized third party plugins: Gather KFX-ZIP (from KFX Input) (1, 49, 0) && DeDRM (7, 2, 1) && Package KFX (from KFX Input) (1, 49, 0) && EpubMerge (2, 13, 0) && EpubSplit (3, 3, 0) && FanFicFare (4, 13, 0) && KFX metadata reader (from KFX Input) (1, 49, 0) && KFX Input (1, 49, 0) && KindleUnpack - The Plugin (0, 83, 1)
Turning on automatic hidpi scaling
devicePixelRatio: 1.0
logicalDpi: 96.0 x 96.0
physicalDpi: 90.21564482029598 x 90.10135135135135
Using calibre Qt style: True
[0.00] Starting up...
[0.02] Showing splash screen...
[0.39] splash screen shown
[0.39] Initializing db...
[0.39] db initialized
[0.39] Constructing main UI...
[1.95] main UI initialized...
[1.95] Hiding splash screen
Starting QuickView
Storage number map:
{(7, 0): [(2, 'C')],
 (7, 1): [(4, 'F'), (6, 'G')],
 (7, 2): [(1, 'J')],
 (7, 3): [(1, 'I')],
 (7, 4): [(1, 'D')],
 (7, 5): [(1, 'H')],
 (7, 6): [(2, 'E')],
 (7, 7): [(1, 'K')]}
Storage number for USBSTOR\DISK&VEN_KINDLE&PROD_INTERNAL_STORAGE&REV_0401\G000T614110709B5&0: StorageDeviceNumber(type=7, number=7, partition_number=0)
Drive letters for USBDevice(vendor_id=0x1949 product_id=0x324 bcd=0x401 devid=usb\vid_1949&pid_0324&rev_0401 devinst=18)
{'drive_letters': ['K'],
 'pnp_id_map': {'K': '\\\\?\\usbstor#disk&ven_kindle&prod_internal_storage&rev_0401#g000t614110709b5&0#{53f56307-b6bf-11d0-94f2-00a0c91efb8b}'},
 'readonly_drives': set(),
 'sort_map': {'K': (7, 1)}}
Syncing cover thumbnails to workaround amazon cover bug
Restored 0 cover thumbnails that were destroyed by Amazon
Job: 0 Recupera informazioni sul dispositivo started
DeviceJob: 0 Recupera informazioni sul dispositivo done, calling callback
DeviceJob: 0 Recupera informazioni sul dispositivo callback returned
Job: 1 Imposta informazioni sulla biblioteca started
DeviceJob: 1 Imposta informazioni sulla biblioteca done, calling callback
DeviceJob: 1 Imposta informazioni sulla biblioteca callback returned
Job: 2 Recupera la lista dei libri del dispositivo started
DEBUG:    0.0 USBMS: Fetching list of books from device. Device= KINDLE2 oncard= None
DEBUG:    0.0 USBMS: dirs are: K:\ documents
Job: 0 Recupera informazioni sul dispositivo finished
Nessun dettaglio disponibile.
Job: 1 Imposta informazioni sulla biblioteca finished
Nessun dettaglio disponibile.
DEBUG:    8.4 USBMS: scan from root False K:\documents
DEBUG:   24.3 USBMS: count found in cache: 4599, count of files in metadata: 4599, need_sync: False
DEBUG:   24.3 USBMS: Finished fetching list of books from device. oncard= None
DEBUG:   24.3 USBMS: Fetching list of books from device. Device= KINDLE2 oncard= carda
DEBUG:   24.3 USBMS: Fetching list of books from device. Device= KINDLE2 oncard= cardb
DeviceJob: 2 Recupera la lista dei libri del dispositivo done, calling callback
DeviceJob: metadata_downloaded: Starting set_books_in_library
DeviceJob: set_books_in_library: books to process= 4599
DeviceJob: set_books_in_library finished: time= 0.05884265899658203
DeviceJob: metadata_downloaded: updating views
DeviceJob: metadata_downloaded: syncing
DeviceJob: metadata_downloaded: refreshing ondevice
DeviceJob: metadata_downloaded: sending metadata_available signal
DeviceJob: 2 Recupera la lista dei libri del dispositivo callback returned
Job: 2 Recupera la lista dei libri del dispositivo finished
Nessun dettaglio disponibile.
[41.78] splash screen hidden
[41.78] Started up in 41.78 seconds with 9 books
Worker Launch took: 0.00 seconds
Worker Launch took: 0.05 seconds
Job: 4 Converti libro 1 di 1 (The Mythology of Global Warming_ Climate Change Fiction vs. Scientific Facts) finished
Converti libro 1 di 1 (The Mythology of Global Warming_ Climate Change Fiction vs. Scientific Facts)
	DeDRM v7.2.1: Trying to decrypt ovp1jbhz.mobi
	Using Library AlfCrypto DLL/DYLIB/SO
	Using Library AlfCrypto DLL/DYLIB/SO
	MobiDeDrm v1.0.
	Copyright © 2008-2020 The Dark Reverser, Apprentice Harper et al.
	Decrypting Mobipocket 4 ebook: THE MYTHOLOGY OF GLOBAL WARMING: Climate Change Fiction vs. Scientific Facts
	Got DSN key from database default_key
	Got DSN key from database default_key_2
	Found 6 keys to try after 0.1 seconds
	Crypto Type is: 0
	This book is not encrypted.
	Decryption succeeded after 0.1 seconds
	DeDRM v7.2.1: Finished after 0.1 seconds
	Conversion options changed from defaults:
	  cover: 'C:\\Users\\luigi\\AppData\\Local\\Temp\\calibre_y1u6m509\\sky41xw1.jpeg'
	  verbose: 2
	  read_metadata_from_opf: 'C:\\Users\\luigi\\AppData\\Local\\Temp\\calibre_y1u6m509\\bll_vipx.opf'
	  output_profile: 'kindle_pw3'
	Resolved conversion options
	calibre version: 5.43.0
	{'asciiize': False,
	 'author_sort': None,
	 'authors': None,
	 'base_font_size': 0.0,
	 'book_producer': None,
	 'change_justification': 'original',
	 'chapter': "//*[((name()='h1' or name()='h2') and re:test(., "
	            "'\\s*((chapter|book|section|part)\\s+)|((prolog|prologue|epilogue)(\\s+|$))', "
	            "'i')) or @class = 'chapter']",
	 'chapter_mark': 'pagebreak',
	 'comments': None,
	 'cover': 'C:\\Users\\luigi\\AppData\\Local\\Temp\\calibre_y1u6m509\\sky41xw1.jpeg',
	 'debug_pipeline': None,
	 'dehyphenate': True,
	 'delete_blank_paragraphs': True,
	 'disable_font_rescaling': False,
	 'dont_compress': False,
	 'duplicate_links_in_toc': False,
	 'embed_all_fonts': False,
	 'embed_font_family': None,
	 'enable_heuristics': False,
	 'expand_css': False,
	 'extra_css': None,
	 'extract_to': None,
	 'filter_css': '',
	 'fix_indents': True,
	 'font_size_mapping': None,
	 'format_scene_breaks': True,
	 'html_unwrap_factor': 0.4,
	 'input_encoding': None,
	 'input_profile': <calibre.customize.profiles.InputProfile object at 0x0000021F56553490>,
	 'insert_blank_line': False,
	 'insert_blank_line_size': 0.5,
	 'insert_metadata': False,
	 'isbn': None,
	 'italicize_common_cases': True,
	 'keep_ligatures': False,
	 'language': None,
	 'level1_toc': None,
	 'level2_toc': None,
	 'level3_toc': None,
	 'line_height': 0.0,
	 'linearize_tables': False,
	 'margin_bottom': 5.0,
	 'margin_left': 5.0,
	 'margin_right': 5.0,
	 'margin_top': 5.0,
	 'markup_chapter_headings': True,
	 'max_toc_links': 50,
	 'minimum_line_height': 120.0,
	 'mobi_toc_at_start': False,
	 'no_chapters_in_toc': False,
	 'no_inline_navbars': False,
	 'no_inline_toc': False,
	 'output_profile': <calibre.customize.profiles.KindlePaperWhite3Output object at 0x0000021F56553AC0>,
	 'page_breaks_before': "//*[name()='h1' or name()='h2']",
	 'prefer_author_sort': False,
	 'prefer_metadata_cover': False,
	 'pretty_print': False,
	 'pubdate': None,
	 'publisher': None,
	 'rating': None,
	 'read_metadata_from_opf': 'C:\\Users\\luigi\\AppData\\Local\\Temp\\calibre_y1u6m509\\bll_vipx.opf',
	 'remove_fake_margins': True,
	 'remove_first_image': False,
	 'remove_paragraph_spacing': False,
	 'remove_paragraph_spacing_indent_size': 1.5,
	 'renumber_headings': True,
	 'replace_scene_breaks': '',
	 'search_replace': '[]',
	 'series': None,
	 'series_index': None,
	 'share_not_sync': False,
	 'smarten_punctuation': False,
	 'sr1_replace': None,
	 'sr1_search': None,
	 'sr2_replace': None,
	 'sr2_search': None,
	 'sr3_replace': None,
	 'sr3_search': None,
	 'start_reading_at': None,
	 'subset_embedded_fonts': False,
	 'tags': None,
	 'timestamp': None,
	 'title': None,
	 'title_sort': None,
	 'toc_filter': None,
	 'toc_threshold': 6,
	 'toc_title': None,
	 'transform_css_rules': '[]',
	 'transform_html_rules': '[]',
	 'unsmarten_punctuation': False,
	 'unwrap_lines': True,
	 'use_auto_toc': False,
	 'verbose': 2}
	DeDRM v7.2.1: Trying to decrypt 3ge2v0pb.mobi
	MobiDeDrm v1.0.
	Copyright © 2008-2020 The Dark Reverser, Apprentice Harper et al.
	Decrypting Mobipocket 4 ebook: THE MYTHOLOGY OF GLOBAL WARMING: Climate Change Fiction vs. Scientific Facts
	Got DSN key from database default_key
	Got DSN key from database default_key_2
	Found 6 keys to try after 0.0 seconds
	Crypto Type is: 0
	This book is not encrypted.
	Decryption succeeded after 0.0 seconds
	DeDRM v7.2.1: Finished after 0.0 seconds
	InputFormatPlugin: MOBI Input running
	on C:\Users\luigi\AppData\Local\Temp\calibre_y1u6m509\jd1qnnt2.mobi
	Extracting text...
	Adding anchors...
	Extracting images...
	Cleaning up HTML...
	Parsing HTML...
	Malformed markup, parsing using html5-parser
	Converting style information to CSS...
	Creating OPF...
	Parsing all content...
	Parsing styles.css ...
	Parsing index.html ...
	Initial parse failed, using more forgiving parsers
	Parsing index.html as HTML
	HTML 5 parsing failed, falling back to older parsers
	Traceback (most recent call last):
	  File "calibre\ebooks\oeb\parse_utils.py", line 211, in parse_html
	  File "calibre\utils\xml_parse.py", line 26, in safe_xml_fromstring
	  File "src/lxml/etree.pyx", line 3237, in lxml.etree.fromstring
	  File "src/lxml/parser.pxi", line 1896, in lxml.etree._parseMemoryDocument
	  File "src/lxml/parser.pxi", line 1777, in lxml.etree._parseDoc
	  File "src/lxml/parser.pxi", line 1082, in lxml.etree._BaseParser._parseUnicodeDoc
	  File "src/lxml/parser.pxi", line 615, in lxml.etree._ParserContext._handleParseResultDoc
	  File "src/lxml/parser.pxi", line 725, in lxml.etree._handleParseResult
	  File "src/lxml/parser.pxi", line 654, in lxml.etree._raiseParseError
	  File "<string>", line 8
	lxml.etree.XMLSyntaxError: Attribute _ redefined, line 8, column 1587
	
	During handling of the above exception, another exception occurred:
	
	Traceback (most recent call last):
	  File "calibre\ebooks\oeb\parse_utils.py", line 218, in parse_html
	  File "calibre\utils\xml_parse.py", line 26, in safe_xml_fromstring
	  File "src/lxml/etree.pyx", line 3237, in lxml.etree.fromstring
	  File "src/lxml/parser.pxi", line 1896, in lxml.etree._parseMemoryDocument
	  File "src/lxml/parser.pxi", line 1777, in lxml.etree._parseDoc
	  File "src/lxml/parser.pxi", line 1082, in lxml.etree._BaseParser._parseUnicodeDoc
	  File "src/lxml/parser.pxi", line 615, in lxml.etree._ParserContext._handleParseResultDoc
	  File "src/lxml/parser.pxi", line 725, in lxml.etree._handleParseResult
	  File "src/lxml/parser.pxi", line 654, in lxml.etree._raiseParseError
	  File "<string>", line 8
	lxml.etree.XMLSyntaxError: Attribute _ redefined, line 8, column 1587
	
	During handling of the above exception, another exception occurred:
	
	Traceback (most recent call last):
	  File "calibre\ebooks\oeb\parse_utils.py", line 224, in parse_html
	  File "calibre\ebooks\oeb\parse_utils.py", line 105, in html5_parse
	ValueError: HTML 5 parsing resulted in a tree with nesting depth > 100
	
	Forcing index.html into XHTML namespace
	Generating default TOC from spine...
	Merging user specified metadata...
	Detecting structure...
	Auto generated TOC with 0 entries.
	Flattening CSS and remapping font sizes...
	Source base font size is 12.00000pt
	Removing fake margins...
	Cleaning up manifest...
	Trimming unused files from manifest...
	Trimming 'images/00002.jpg' from manifest
	Trimming 'images/00001.jpg' from manifest
	Creating AZW3 Output...
	Serializing resources...
	Splitting markup on page breaks and flow limits, if any...
	Creating KF8 output
		Generating KF8 markup...
	Tag fm______m5_ma__ml__m___ has no aid and a too large chunk size. Adding anyway.
		Compressing markup...
		Creating indices...
	Document has no ToC, MOBI will have no NCX index
	AZW3 output written to C:\Users\luigi\AppData\Local\Temp\calibre_y1u6m509\72iqwii3.azw3
Traceback (most recent call last):
  File "calibre\devices\usbms\driver.py", line 255, in update_booklist
  File "calibre\devices\usbms\driver.py", line 556, in book_from_path
OSError: [WinError 1392] La directory o il file è danneggiato e illeggibile: 'K:\\documents\\Georgi Stankov.txt'

[jhowell]

That is caused by the same issue as discussed this thread: Kindle Mobi format will not open in Calibre