Conversion error from ePub to MOBI

[PauloRosa]

I'm trying to convert an epub to mobi and am getting an error:

this is the error log:

Spoiler:

calibre, version 5.10.1 (win32, embedded-python: True)
Erro ao converter: Falha: Converter livro 1 de 1 (A sociedade do anel)

Converter livro 1 de 1 (A sociedade do anel)
Conversion options changed from defaults:
cover: 'C:\\Users\\paulo\\AppData\\Local\\Temp\\calibre_q mp03h_8\\c1x6s2fy.jpeg'
verbose: 2
output_profile: 'kindle_pw3'
read_metadata_from_opf: 'C:\\Users\\paulo\\AppData\\Local\\Temp\\calibre_q mp03h_8\\191i84fq.opf'
Resolved conversion options
calibre version: 5.10.1
{'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|p rologue|epilogue)(\\s+|$))', "
"'i')) or @class = 'chapter']",
'chapter_mark': 'pagebreak',
'comments': None,
'cover': 'C:\\Users\\paulo\\AppData\\Local\\Temp\\calibre_q mp03h_8\\c1x6s2fy.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 0x0000018FAC765A60>,
'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_file_type': 'old',
'mobi_ignore_margins': False,
'mobi_keep_original_images': False,
'mobi_toc_at_start': False,
'no_chapters_in_toc': False,
'no_inline_navbars': True,
'no_inline_toc': False,
'output_profile': <calibre.customize.profiles.KindlePaperWhite3Outpu t object at 0x0000018FAC77A0A0>,
'page_breaks_before': '/',
'personal_doc': '[PDOC]',
'prefer_author_sort': False,
'prefer_metadata_cover': False,
'pretty_print': False,
'pubdate': None,
'publisher': None,
'rating': None,
'read_metadata_from_opf': 'C:\\Users\\paulo\\AppData\\Local\\Temp\\calibre_q mp03h_8\\191i84fq.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': '[]',
'unsmarten_punctuation': False,
'unwrap_lines': True,
'use_auto_toc': False,
'verbose': 2}
InputFormatPlugin: EPUB Input running
on C:\Users\paulo\AppData\Local\Temp\calibre_qmp03h_8 \q9ig6xfa.epub
Found HTML cover OEBPS/Text/SdA1-Capa.xhtml
Parsing all content...
Traceback (most recent call last):
File "runpy.py", line 194, in _run_module_as_main
File "runpy.py", line 87, in _run_code
File "site.py", line 82, in <module>
File "site.py", line 77, in main
File "site.py", line 49, in run_entry_point
File "calibre\utils\ipc\worker.py", line 216, in main
File "calibre\gui2\convert\gui_conversion.py", line 41, in gui_convert_override
File "calibre\gui2\convert\gui_conversion.py", line 28, in gui_convert
File "calibre\ebooks\conversion\plumber.py", line 1118, in run
File "calibre\ebooks\conversion\plumber.py", line 1316, in create_oebbook
File "calibre\ebooks\oeb\reader.py", line 72, in __call__
File "calibre\ebooks\oeb\reader.py", line 699, in _all_from_opf
File "calibre\ebooks\oeb\reader.py", line 344, in _spine_from_opf
calibre.ebooks.oeb.base.OEBError: Spine is empty

Can anybody help?

[kovidgoyal]

That error indicates your epub file is invalid.

[PauloRosa]

What bugs me is that I can read it in calibre...
It opens apparently alright

[DNSB]

I'd suggest trying two options.

The first would be to use calibre to do an epub to epub conversion before the conversion to mobi.

The second would be opening the epub in calibre's editor after installing the epubcheck plugin. Check with both the builtin error check and epubcheck. Prepare to be disgusted by many commercial epubs that give multiple pages of errors.

[kovidgoyal]

I would be very surprised if there is a book that calibre can view but not convert. If that is really the case, attach the epub file to a bug report.