Calibre E-book Content Server not working on Ubuntu 22.04

user693336

3/11/24, 2:07 AM

Background Info:

I've used Calibre for many, many years. I use the content server to allow access to my libraries over my local network. However, sometime in December the content server stopped working. I first thought that a firewall setting may have been changed. But checking the firewall, routers and routing tables shows the port I run the content server is are open. I didn't really pursue this issue as I found that starting the calibre server as my regular user gave me access. However, I have become frustrated with the lack of access to add or modify my library while sitting at my workstation on which calibre is run. I like the easy access that running calibre desktop gives me. Today I decided to tackle this issue and learned that Calibre works on the network if ran with sudo or as root. However, running it as my standard user (which I have always done) does not work. So I expect this is a permission issue...

System: Ubuntu 22.04 with latest updates (I run apt update and apt upgrade every morning). Calibre: Versions from 6.10 on have had this issue. I am currently on 6.14.

Python: I have ran Calibre with python versions 3.7 - 3.11 using update-alternatives and have the same results.

Query: What do I need to do to be able to run calibre's content server as my regular user account instead of using sudo?

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Terrance

3/11/24, 4:59 AM

Probably the first time you launched Calibre as a root user it changed all the ownership of the `~/.config/calibre` directory and its contents to `root` instead of your user. If that directory and its contents are owned by `root` you will not be able to launch it correctly. Show the output of `ls -al ~/.config/calibre`

user693336

3/17/24, 10:53 PM

Sorry, I had a medical procedure and was offline for a few days. Thanks for the reply. I listed the files in the ~/.config/calibre directory and they all show they are owned by my standard user account. So the permission issue is not with the ~/.config/calibre directory. Any other ideas?

Terrance

3/18/24, 10:47 PM

Maybe check the permissions of both the `calibre` and `calibre-server` apps. `ls -al /opt/calibre/calibre-server` and `ls -al /opt/calibre/calibre`

user693336

3/19/24, 3:03 AM

The permissions on both (and everything under /opt) are owner and group is root. permissions are -rwxr-xr-x, I believe that's owner can read, write, and execute, group can read and execute, and others can read and execute. These are the same permissions for other things in /opt like my web browser which I can run as my regular user. For completeness: ls -al /opt/calibre/calibre-server -rwxr-xr-x 1 root root 14472 Mar 9 17:24 /opt/calibre/calibre-server, ls -al /opt/calibre/calibre -rwxr-xr-x 1 root root 14472 Mar 9 17:24 /opt/calibre/calibre

Terrance

3/19/24, 3:18 AM

One other question and then I am officially out of ideas here. Both calibre and calibre-server work fine for my user account without any issues. What Kernel version are you running? Ubuntu 22.04.2 LTS defaults to the 5.19 Kernel on a clean install, and unfortunately I bumped into issues with it where drivers would fail in the 5.19, then work if I reinstalled the driver, then fail again. It was very unpredictable. I went back to just the 5.15 Kernel and have not had any issues. Beyond the Kernel, I am out of ideas. Sorry about that!

user693336

3/23/24, 3:24 AM

The kernel version via uname -r is 5.15.0-67-generic. Here I should say that I upgraded to 22.04 from 20.04. I do run apt update and apt upgrade daily. I keep that last three kernel version on the system as I have had issues with some of the software I use almost daily like Quartus II and ModelSim. I will try rolling back to another kernel version and update this post with the results. Thank you so much Terrance for you help!

user693336

4/4/24, 4:29 AM

Solved - After weeks of messing with this, I solved the issue tonight! In the Advanced Setting for the Content Server, the max size for a single HTTP header was set to 0.0. The however didn't affect the server when run from the terminal. I set this value to 2 Kb first and then played with the value and settled on 10kb. But anything from > 2Kb seemed to work just fine. Still, I increased it to provide some headroom. I should note that I have no idea how this value was changed and why the issue occurred right after an update to a version back around December.

Terrance

4/4/24, 4:41 AM

You should write that up as an answer. I'll totally upvote it! Good job!!

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