[MJLee]

I updated to 5.0.1 and now the viewer won't open, or rather it will but but give a warning:

calibre, version 5.0.1
ERROR: Loading book failed: Failed to open the book at C:\Users\miamu\Calibre Library\Unknown 1001\Neon Snowman (1763)\Neon Snowman - Unknown 1001.kepub. Click "Show details" for more info.

Failed to convert book: C:\Users\miamu\Calibre Library\Unknown 1001\Neon Snowman (1763)\Neon Snowman - Unknown 1001.kepub with error:
Failed to initialize plugin: 'C:\\Users\\miamu\\AppData\\Roaming\\calibre\\plug ins\\KePub Metadata Writer.zip'
InputFormatPlugin: KePub Input running
on C:\Users\miamu\Calibre Library\Unknown 1001\Neon Snowman (1763)\Neon Snowman - Unknown 1001.kepub
KEPUBInput::convert - start
KEPUB appears to be invalid ZIP file, trying a more forgiving ZIP parser
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 89, in <module>
File "site.py", line 84, in main
File "site.py", line 55, in run_entry_point
File "site-packages\calibre\utils\ipc\worker.py", line 195, in main
File "<string>", line 1, in <module>
File "site-packages\calibre\srv\render_book.py", line 871, in viewer_main
File "site-packages\calibre\srv\render_book.py", line 862, in render_for_viewer
File "site-packages\calibre\srv\render_book.py", line 839, in render
File "site-packages\calibre\ebooks\oeb\iterator\book.py", line 63, in extract_book
File "site-packages\calibre\customize\conversion.py", line 245, in __call__
File "calibre_plugins.kepubin.conversion.kepub_inpu t", line 89, in convert
AttributeError: module 'os' has no attribute 'getcwdu'

4.9 had the same problem with some books but now this applies to all books. However if I manually open them in epub, no problem. Solutions?

It seems it's kepub which is the problem and calibre fails to open in kepub which is fine with me. How do I reset so it opens in epub?

Edit: I updated all Kobo plugins and the viewer opens the book but not before asking me to chose an app for viewing kepub. I've gone into the Preferences and clicked that I don't want to view it in kepub but it persists in asking me, which is very irritating.

Dubbel edit: ok, I directed it to open kepub in the viewer which is fine but now it opens in kepub first, while I want it to open in epub. Any suggestions on how to reverse the format order it opens in?

Edit 3: If I have dl a book (fanfic btw) in only epub it opens in epub without problem.