[Joseph The Grave]

Originally Posted by DNSB

Considering that calibre's ebook-viewer is very forgiving of errors in an epub, I'm not sure how many other programs will be more forgiving. Perhaps cleaning up the epub before attempting to view it might be a good idea.

I tried 2 or 3 other epub viewers, including Adobe Digital Editions, and they all open the troublesome epubs fine. It's just Calibre's ebook viewer that has the issue. But since calibre's ebook viewer is by far the best epub viewer I've used, I'd certainly prefer to use it over all others. Yes, no doubt the epub in question (someone else put it together, btw... I have no real expertise in these matters) is sloppily put together and is in a very bad state, as someone said. Are there any programs that might help in auto-cleaning it up? (see below for specific error msg)

Originally Posted by BetterRed

Does the viewer handle Fixed Layout EPUBS?

The OP said the troublesome books are 'large custom ebooks'.

BR

I don't even know what "Fixed Layout Epubs" are lol

Originally Posted by davidfor

That's a good point. I don't think I have seen the viewer fail to open a book that wasn't in very bad state. Sometimes it can take a while, but, it very rare for the book not to open.

And @Joseph The Grave has said there was an error, but, has not actually mentioned what the error is. That might tell us what is the real problem.

As mentioned in previous posts, yes, this happens VERY rarely but it's still annoying when it does. Here's the specific error message in its entirety:

Spoiler:

calibre, version 5.44.0
ERROR: Loading book failed: Failed to open the book at J:\Downloads\Margaret St. Clair - COMPLEAT Collected Short SFF Stories, The.epub. Click "Show details" for more info

Failed to convert book: J:\Downloads\Margaret St. Clair - COMPLEAT Collected Short SFF Stories, The.epub with error:
InputFormatPlugin: EPUB Input running
on J:\Downloads\Margaret St. Clair - COMPLEAT Collected Short SFF Stories, The.epub
Found HTML cover titlepage.xhtml
Failed to run pipe worker with command: from calibre.srv.render_book import viewer_main; viewer_main()
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 196, in main
File "<string>", line 1, in <module>
File "calibre\srv\render_book.py", line 823, in viewer_main
File "calibre\srv\render_book.py", line 814, in render_for_viewer
File "calibre\srv\render_book.py", line 792, in render
File "calibre\srv\render_book.py", line 646, in process_exploded_book
File "calibre\srv\render_book.py", line 496, in __call__
Exception: Render worker failed with error:
Failed to run pipe worker with command: from calibre.srv.render_book import worker_main; worker_main()

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 196, in main

File "<string>", line 1, in <module>

File "calibre\srv\render_book.py", line 506, in worker_main

File "calibre\srv\render_book.py", line 561, in process_book_files

File "calibre\srv\render_book.py", line 405, in transform_html

File "calibre\srv\render_book.py", line 394, in handle_link

File "calibre\srv\render_book.py", line 104, in link_replacer

File "calibre\ebooks\oeb\polish\container.py", line 529, in href_to_name

File "calibre\ebooks\oeb\polish\container.py", line 121, in href_to_name

File "calibre\ebooks\oeb\polish\container.py", line 97, in abspath_to_name

File "ntpath.py", line 703, in relpath

ValueError: path is on mount '\\\\-\\JfONDAY', start on mount 'N:'