In my case, the test_4 version failed. It looks like it worked regarding the ToC, but overall it came back saying it failed:
Code:
calibre, version 5.41.0
ERROR: Modify ePub failed: No ePub files were updated
Modify ePubs version (1, 7, 1)
Logfile for book ID 4 (Pride and Prejudice / Jane Austen)
Job details 4
Modifying: /tmp/calibre_5.41.0_tmp_n1qkgbl5/qx0mehm1_modify_epub/4.epub
Parsing xml file: content.opf
Parsing xml file: toc.ncx
Looking for broken links in the NCX
ncx name: toc.ncx
Name map 0: jacket.xhtml, text/chapter-01.html, text/chapter-02.html, text/chapter-03.html, text/chapter-04.html
Name map 5: text/chapter-05.html, text/chapter-06.html, text/chapter-07.html, text/chapter-08.html, text/chapter-09.html
Name map 10: text/chapter-10.html, text/chapter-11.html, text/chapter-12.html, text/chapter-13.html, text/chapter-14.html
Name map 15: text/chapter-15.html, text/chapter-16.html, text/chapter-17.html, text/chapter-18.html, text/chapter-19.html
Name map 20: text/chapter-20.html, text/chapter-21.html, text/chapter-22.html, text/chapter-23.html, text/chapter-24.html
Name map 25: text/chapter-25.html, text/chapter-26.html, text/chapter-27.html, text/chapter-28.html, text/chapter-29.html
Name map 30: text/chapter-30.html, text/chapter-31.html, text/chapter-32.html, text/chapter-33.html, text/chapter-34.html
Name map 35: text/chapter-35.html, text/chapter-36.html, text/chapter-37.html, text/chapter-38.html, text/chapter-39.html
Name map 40: text/chapter-40.html, text/chapter-41.html, text/chapter-42.html, text/chapter-43.html, text/chapter-44.html
Name map 45: text/chapter-45.html, text/chapter-46.html, text/chapter-47.html, text/chapter-48.html, text/chapter-49.html
Name map 50: text/chapter-50.html, text/chapter-51.html, text/chapter-52.html, text/chapter-53.html, text/chapter-54.html
Name map 55: text/chapter-55.html, text/chapter-56.html, text/chapter-57.html, text/chapter-58.html, text/chapter-59.html
Name map 60: text/chapter-60.html, text/chapter-61.html, text/titleauthor.html, text/titlepage.xhtml, toc.xhtml
Looping over ncx entries
ncx src=text/titleauthor.html, rel path=text/titleauthor.html, in map: True
ncx src=text/chapter-01.html, rel path=text/chapter-01.html, in map: True
ncx src=text/chapter-02.html, rel path=text/chapter-02.html, in map: True
ncx src=text/chapter-03.html, rel path=text/chapter-03.html, in map: True
ncx src=text/chapter-04.html, rel path=text/chapter-04.html, in map: True
ncx src=text/chapter-05.html, rel path=text/chapter-05.html, in map: True
ncx src=text/chapter-06.html, rel path=text/chapter-06.html, in map: True
ncx src=text/chapter-07.html, rel path=text/chapter-07.html, in map: True
ncx src=text/chapter-08.html, rel path=text/chapter-08.html, in map: True
ncx src=text/chapter-09.html, rel path=text/chapter-09.html, in map: True
ncx src=text/chapter-10.html, rel path=text/chapter-10.html, in map: True
ncx src=text/chapter-11.html, rel path=text/chapter-11.html, in map: True
ncx src=text/chapter-12.html, rel path=text/chapter-12.html, in map: True
ncx src=text/chapter-13.html, rel path=text/chapter-13.html, in map: True
ncx src=text/chapter-14.html, rel path=text/chapter-14.html, in map: True
ncx src=text/chapter-15.html, rel path=text/chapter-15.html, in map: True
ncx src=text/chapter-16.html, rel path=text/chapter-16.html, in map: True
ncx src=text/chapter-17.html, rel path=text/chapter-17.html, in map: True
ncx src=text/chapter-18.html, rel path=text/chapter-18.html, in map: True
ncx src=text/chapter-19.html, rel path=text/chapter-19.html, in map: True
ncx src=text/chapter-20.html, rel path=text/chapter-20.html, in map: True
ncx src=text/chapter-21.html, rel path=text/chapter-21.html, in map: True
ncx src=text/chapter-22.html, rel path=text/chapter-22.html, in map: True
ncx src=text/chapter-23.html, rel path=text/chapter-23.html, in map: True
ncx src=text/chapter-24.html, rel path=text/chapter-24.html, in map: True
ncx src=text/chapter-25.html, rel path=text/chapter-25.html, in map: True
ncx src=text/chapter-26.html, rel path=text/chapter-26.html, in map: True
ncx src=text/chapter-27.html, rel path=text/chapter-27.html, in map: True
ncx src=text/chapter-28.html, rel path=text/chapter-28.html, in map: True
ncx src=text/chapter-29.html, rel path=text/chapter-29.html, in map: True
ncx src=text/chapter-30.html, rel path=text/chapter-30.html, in map: True
ncx src=text/chapter-31.html, rel path=text/chapter-31.html, in map: True
ncx src=text/chapter-32.html, rel path=text/chapter-32.html, in map: True
ncx src=text/chapter-33.html, rel path=text/chapter-33.html, in map: True
ncx src=text/chapter-34.html, rel path=text/chapter-34.html, in map: True
ncx src=text/chapter-35.html, rel path=text/chapter-35.html, in map: True
ncx src=text/chapter-36.html, rel path=text/chapter-36.html, in map: True
ncx src=text/chapter-37.html, rel path=text/chapter-37.html, in map: True
ncx src=text/chapter-38.html, rel path=text/chapter-38.html, in map: True
ncx src=text/chapter-39.html, rel path=text/chapter-39.html, in map: True
ncx src=text/chapter-40.html, rel path=text/chapter-40.html, in map: True
ncx src=text/chapter-41.html, rel path=text/chapter-41.html, in map: True
ncx src=text/chapter-42.html, rel path=text/chapter-42.html, in map: True
ncx src=text/chapter-43.html, rel path=text/chapter-43.html, in map: True
ncx src=text/chapter-44.html, rel path=text/chapter-44.html, in map: True
ncx src=text/chapter-45.html, rel path=text/chapter-45.html, in map: True
ncx src=text/chapter-46.html, rel path=text/chapter-46.html, in map: True
ncx src=text/chapter-47.html, rel path=text/chapter-47.html, in map: True
ncx src=text/chapter-48.html, rel path=text/chapter-48.html, in map: True
ncx src=text/chapter-49.html, rel path=text/chapter-49.html, in map: True
ncx src=text/chapter-50.html, rel path=text/chapter-50.html, in map: True
ncx src=text/chapter-51.html, rel path=text/chapter-51.html, in map: True
ncx src=text/chapter-52.html, rel path=text/chapter-52.html, in map: True
ncx src=text/chapter-53.html, rel path=text/chapter-53.html, in map: True
ncx src=text/chapter-54.html, rel path=text/chapter-54.html, in map: True
ncx src=text/chapter-55.html, rel path=text/chapter-55.html, in map: True
ncx src=text/chapter-56.html, rel path=text/chapter-56.html, in map: True
ncx src=text/chapter-57.html, rel path=text/chapter-57.html, in map: True
ncx src=text/chapter-58.html, rel path=text/chapter-58.html, in map: True
ncx src=text/chapter-59.html, rel path=text/chapter-59.html, in map: True
ncx src=text/chapter-60.html, rel path=text/chapter-60.html, in map: True
ncx src=text/chapter-61.html, rel path=text/chapter-61.html, in map: True
ePub not changed after 0.04 seconds