[DNSB]

For what it may be worth, I tried converting a text version of The Owl and the Pussy Cat poem to ePub using calibre 7.25. Regular expression error?

The conversion failed and the log file is in the spoiler.

Spoiler:

calibre, version 7.25.0 (win32, embedded-python: True)
Conversion error: Failed: Convert book 1 of 1 (The Owl and the Pussy-Cat)

Convert book 1 of 1 (The Owl and the Pussy-Cat)
Conversion options changed from defaults:
  output_profile: 'tablet'
  verbose: 2
  margin_right: 0.0
  margin_left: 0.0
  change_justification: 'left'
  margin_bottom: 0.0
  extra_css: 'body {\n-epub-hyphens: none;\nadobe-hyphenate: none;\n-webkit-hyphens: none;\n-moz-hyphens: none;\nhyphens: none;\n}'
  preserve_cover_aspect_ratio: True
  read_metadata_from_opf: 'C:\\Users\\dbowe\\AppData\\Local\\Temp\\calibre_64vjz1m8\\vjbflenm.opf'
  enable_heuristics: True
  margin_top: 0.0
Resolved conversion options
calibre version: 7.25.0
{'add_alt_text_to_img': False,
 'asciiize': False,
 'author_sort': None,
 'authors': None,
 'base_font_size': 0.0,
 'book_producer': None,
 'change_justification': 'left',
 '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': None,
 'debug_pipeline': None,
 'dehyphenate': True,
 'delete_blank_paragraphs': True,
 'disable_font_rescaling': False,
 'dont_split_on_page_breaks': False,
 'duplicate_links_in_toc': False,
 'embed_all_fonts': False,
 'embed_font_family': None,
 'enable_heuristics': True,
 'epub_flatten': False,
 'epub_inline_toc': False,
 'epub_max_image_size': 'none',
 'epub_toc_at_end': False,
 'epub_version': '2',
 'expand_css': False,
 'extra_css': 'body {\n'
              '-epub-hyphens: none;\n'
              'adobe-hyphenate: none;\n'
              '-webkit-hyphens: none;\n'
              '-moz-hyphens: none;\n'
              'hyphens: none;\n'
              '}',
 'extract_to': None,
 'filter_css': '',
 'fix_indents': True,
 'flow_size': 260,
 'font_size_mapping': None,
 'format_scene_breaks': True,
 'formatting_type': 'auto',
 'html_unwrap_factor': 0.4,
 'input_encoding': None,
 'input_profile': <calibre.customize.profiles.InputProfile object at 0x0000022712B5BE90>,
 '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': 0.0,
 'margin_left': 0.0,
 'margin_right': 0.0,
 'margin_top': 0.0,
 'markdown_extensions': 'footnotes, tables, toc',
 'markup_chapter_headings': True,
 'max_toc_links': 50,
 'minimum_line_height': 120.0,
 'no_chapters_in_toc': False,
 'no_default_epub_cover': False,
 'no_inline_navbars': False,
 'no_svg_cover': False,
 'output_profile': <calibre.customize.profiles.TabletOutput object at 0x0000022712B82E10>,
 'page_breaks_before': "//*[name()='h1' or name()='h2']",
 'paragraph_type': 'auto',
 'prefer_metadata_cover': False,
 'preserve_cover_aspect_ratio': True,
 'preserve_spaces': False,
 'pretty_print': True,
 'pubdate': None,
 'publisher': None,
 'rating': None,
 'read_metadata_from_opf': 'C:\\Users\\dbowe\\AppData\\Local\\Temp\\calibre_64vjz1m8\\vjbflenm.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,
 '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': '[]',
 'txt_in_remove_indents': False,
 'unsmarten_punctuation': False,
 'unwrap_lines': True,
 'use_auto_toc': False,
 'verbose': 2}
InputFormatPlugin: TXT Input running
on C:\Users\dbowe\AppData\Local\Temp\calibre_64vjz1m8\ia710iic.txt
Reading text from file...
Detected input encoding as ascii with a confidence of 100%
Auto detected paragraph type as print
Auto detected formatting as heuristic
Running text through basic conversion...
Language not specified
Creator not specified
Building file list...
	Found files...
		 HTMLFile:0:a:'C:\\Users\\dbowe\\AppData\\Local\\Temp\\calibre_64vjz1m8\\1s9i1_l1_plumber\\index.html'
Normalizing filename cases
Rewriting HTML links
Parsing index.html ...
*********  Heuristic processing HTML  *********
There are 0 blank lines. 0.0 percent blank
minimum chapters required are: 1
found 0 pre-existing headings
Total wordcount is: 242, Average words per section is: 242, Marked up 0 chapters
Hard line breaks check returned True
Median line length is 45, calculated with html format
Fixing hyphenated content
Looking for more split points based on punctuation, currently have 0
Formatting scene breaks
Traceback (most recent call last):
  File "runpy.py", line 198, in _run_module_as_main
  File "runpy.py", line 88, in _run_code
  File "site.py", line 83, in <module>
  File "site.py", line 78, in main
  File "site.py", line 50, in run_entry_point
  File "calibre\utils\ipc\worker.py", line 215, in main
  File "calibre\gui2\convert\gui_conversion.py", line 38, in gui_convert_override
  File "calibre\gui2\convert\gui_conversion.py", line 25, in gui_convert
  File "calibre\ebooks\conversion\plumber.py", line 1128, in run
  File "calibre\customize\conversion.py", line 242, in __call__
  File "calibre\ebooks\conversion\plugins\txt_input.py", line 325, in convert
  File "calibre\ebooks\conversion\plugins\html_input.py", line 109, in convert
  File "calibre\ebooks\conversion\plugins\html_input.py", line 209, in create_oebbook
  File "calibre\ebooks\oeb\base.py", line 1056, in data
  File "calibre\ebooks\oeb\base.py", line 966, in _parse_xhtml
  File "calibre\ebooks\oeb\parse_utils.py", line 203, in parse_html
  File "calibre\ebooks\conversion\preprocess.py", line 614, in __call__
  File "calibre\ebooks\conversion\utils.py", line 879, in __call__
  File "re\__init__.py", line 317, in _subx
  File "re\__init__.py", line 308, in _compile_repl
  File "re\_parser.py", line 1080, in parse_template
re.error: bad escape \u at position 14