Error: Namespace prefix opf for scheme on identifier is not defined

[uwe4711]

Hello,
when I try to convert an ePub to MOBI or AZW3 I get the following error. I have no idea what this means. Can someone please assist. Thank you

Spoiler:

calibre, version 1.3.0 (win32, isfrozen: True)
Konvertierungsfehler: Fehlgeschlagen: Konvertiere Buch 1 von 1 (Stadt der Finsternis)

Konvertiere Buch 1 von 1 (Stadt der Finsternis)
Resolved conversion options
calibre version: 1.3.0
{'asciiize': False,
'author_sort': None,
'authors': None,
'base_font_size': 0.0,
'book_producer': None,
'change_justification': u'original',
'chapter': u"//*[((name()='h1' or name()='h2') and re:test(., '\\s*((chapter|book|section|part)\\s+)|((prolog|pr ologue|epilogue)(\\s+|$))', 'i')) or @class = 'chapter']",
'chapter_mark': u'pagebreak',
'comments': None,
'cover': u'C:\\Users\\name\\AppData\\Local\\Temp\\calibre_f fawny\\8ul32g.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,
'extra_css': None,
'extract_to': None,
'filter_css': u'',
'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 0x0253DD30>,
'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.KindlePaperWhiteOutp ut object at 0x0250AC50>,
'page_breaks_before': u"//*[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': u'C:\\Users\\name\\AppData\\Local\\Temp\\calibre_f fawny\\p9bxij.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': u'',
'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,
'unsmarten_punctuation': False,
'unwrap_lines': True,
'use_auto_toc': False,
'verbose': 2}
InputFormatPlugin: EPUB Input running
on C:\Users\name\AppData\Local\Temp\calibre_ffawny\8i sm3r.epub
Parsing all content...
OPF contains invalid tours section
Python function terminated unexpectedly
Namespace prefix opf for scheme on identifier is not defined, line 18, column 37 (Error Code: 1)
Traceback (most recent call last):
File "site.py", line 132, in main
File "site.py", line 109, in run_entry_point
File "site-packages\calibre\utils\ipc\worker.py", line 189, in main
File "site-packages\calibre\gui2\convert\gui_conversion.py", line 31, in gui_convert_override
File "site-packages\calibre\gui2\convert\gui_conversion.py", line 25, in gui_convert
File "site-packages\calibre\ebooks\conversion\plumber.py", line 1038, in run
File "site-packages\calibre\ebooks\conversion\plumber.py", line 1215, in create_oebbook
File "site-packages\calibre\ebooks\oeb\reader.py", line 70, in __call__
File "site-packages\calibre\ebooks\oeb\reader.py", line 119, in _read_opf
File "lxml.etree.pyx", line 2993, in lxml.etree.fromstring (src\lxml\lxml.etree.c:63285)
File "parser.pxi", line 1617, in lxml.etree._parseMemoryDocument (src\lxml\lxml.etree.c:93571)
File "parser.pxi", line 1488, in lxml.etree._parseDoc (src\lxml\lxml.etree.c:92305)
File "parser.pxi", line 969, in lxml.etree._BaseParser._parseUnicodeDoc (src\lxml\lxml.etree.c:88675)
File "parser.pxi", line 577, in lxml.etree._ParserContext._handleParseResultDoc (src\lxml\lxml.etree.c:84711)
File "parser.pxi", line 676, in lxml.etree._handleParseResult (src\lxml\lxml.etree.c:85816)
File "parser.pxi", line 616, in lxml.etree._raiseParseError (src\lxml\lxml.etree.c:85138)
lxml.etree.XMLSyntaxError: Namespace prefix opf for scheme on identifier is not defined, line 18, column 37

Uwe

[kovidgoyal]

It means the opf file inside your epub is invalid. Look for opf:scheme and replace it with scheme

[uwe4711]

Hi,
thanks for that hint, but to tell you the truth, I don't know what you mean.
I learned, that the OPF-file is inside the epub. Do I have to extract it to change it or how would this replace work. O googled a lot, but could find what you try me to tell.
Thanks

[kovidgoyal]

Right click on the book in calibre and select Tweak Book

[uwe4711]

Thank you, that worked