http://bentasker.i2p/posts/blog/general/containerising-and-deploying-calibres-content-server-to-allow-web-annotations.html
Running calibre_postinstall threw similar exceptions, but it's output also gave a clue about the underlying issue: Failed to import PyQt module: PyQt6.QtWebEngineCore with error: libxkbfile.so.1: cannot open shared object file: No such file or directory Although PyQt6 was installed, it couldn't be imported because some of its dependencies weren't.