[BUG] cannot convert to PDF

[Mat-DB]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

Hi,

I have searched a lot and found a solution. I do have not idea it is the best but it works and would like to share it.

Problem

When trying to convert a EPUB (did not test other formats) to PDF a new task is started. This task almost immediately fails with

Calibre failed with error: ImportError: cannot import name 'QWebEnginePage' from 'qt.webengine' (/app/calibre/lib/calibre-extensions/python-lib.bypy.frozen/qt/webengine.pyc)

Solution

After searching I found the following command,

calibre-debug -c "from PyQt6.QtWebEngineCore import QWebEnginePage; print(QWebEnginePage)"

This gave me the following output, saying it needs libasound.so.2

calibre-debug -c "from PyQt6.QtWebEngineCore import QWebEnginePage; print(QWebEnginePage)"
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 47, in <module>
  File "site.py", line 43, in main
  File "calibre/debug.py", line 242, in main
  File "<string>", line 1, in <module>
  File "bypy-importer.py", line 127, in create_module
ImportError: libasound.so.2: cannot open shared object file: No such file or directory

To solve this I installed libasound2t64 and it was fixed.

apt install libasound2t64 -y

I hope this helps someone or it gets fixed for everyone.
Any feedback is appreciated!

Kind regards,
Matthias

Expected Behavior

The conversion from EPUB to PDF works without errors.

Steps To Reproduce

Try to convert a EPUB to PDF.

Environment

- OS: openmediavault 7.7.13 (Debian 12)
- How docker service was installed: using openmediavault

CPU architecture

x86-64

Docker creation

Docker compose:

---
services:
  calibre-web:
    image: lscr.io/linuxserver/calibre-web:latest
    container_name: calibre-web
    networks:
      - proxy_net
    environment:
      - PUID=${PUID}
      - PGID=${PGID}
      - TZ=${TZ}
      - DOCKER_MODS=linuxserver/mods:universal-calibre #optional
      #- OAUTHLIB_RELAX_TOKEN_SCOPE=1 #optional
    volumes:
      - /sym/appData/calibre-web/config:/config
      - /sym/appData/calibre-web/library:/books
    ports:
      - 8084:8083
    restart: unless-stopped
    security_opt:
      - no-new-privileges:true
      
networks:
  proxy_net:
    name: ${PROXY_NET}
    external: true

Container logs

[2025-07-10 22:03:56,058]  INFO {cps.editbooks:186} converting: book id: 2 from: EPUB to: PDF
[2025-07-10 22:03:56,702]  INFO {cps.tasks.convert:162} Book id 2 - target format of .pdf does not exist. Moving forward with convert.
[2025-07-10 22:03:58,720]  INFO {cps.tasks.convert:209} ebook converter failed with error while converting book
[2025-07-10 22:03:58,721] ERROR {cps.tasks.convert:213} Calibre failed with error: ImportError: cannot import name 'QWebEnginePage' from 'qt.webengine' (/app/calibre/lib/calibre-extensions/python-lib.bypy.frozen/qt/webengine.pyc)

[github-actions]

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[drizuid]

is the source epub fixed layout? calibre does not support fixed layout conversions. failing that, i would ask calibre-web directly, i suspect it's because it requires an actual pdf reader to parse the file for conversion, which calibre-web would not have. our calibre container would likely handle this fine.

[Mat-DB]

is the source epub fixed layout?

How can I check this?
I have no idea about that. I did try multiple books, but they can all have fixed layout of course.

I also look into asking calibre-web support directly.

Thanks!

[drizuid]

How can I check this?

no clue, i just looked at issues on calibre-web's github. we only support the container itself, not the application within the container. I don't personally do conversions in calibre-web, i use calibre which can do it without an issue. Like i said, i suspect the issue is the lack of a pdf parser in the container.

[LinuxServer-CI]

This issue has been automatically marked as stale because it has not had recent activity. This might be due to missing feedback from OP. It will be closed if no further activity occurs. Thank you for your contributions.

[drizuid]

closing this as it would be out of scope for us, suggest OP using the universal install mod to install whatever makes it work for them. With this being the only time i've ever seen anyone bring this up, im not sure we would want to bake this in for all.