Have you opened an issue on repo for the devs to see? might as well go straight to the source.

i’m assuming the flask module here is the flask that is a python framework for building apps. sounds like the dependency wasn’t added to the latest build

I had the exact same problem. I solved it by:

- Deleting the container and image

- Create a task in task scheduler with root user and with the following config

docker run -d \
--name=calibre-web \
-e PUID=1026 \
-e PGID=100 \
-e TZ=Europe/Lisbon \
-e DOCKER_MODS=ghcr.io/linuxserver/mods:universal-calibre \
-e OAUTHLIB_RELAX_TOKEN_SCOPE=1 \
-e TP_THEME=aquamarine \
-p 8083:8083 \
-v /volume1/docker/calibre-web:/config \
-v /volume1/docker/calibre/BibliotecaCalibre:/books \
--restart unless-stopped \
lscr.io/linuxserver/calibre-web

Replace PUID and PGID by your own

It will this time install flask and all necessary python modules. All your data and configs will be preserved