No more comics after Synology Docker image change

I've been running YAC Library Server in a Docker container on my SYN for quite some time now. I've been using the Muallin Docker image for this.

It contains hundreds of comics and PDFs, and everything has been working very well so far. Except for the 7z error, and I'd now like to switch to your own YACReaderLibraryServer image.

The setup went smoothly, but now my database on my iPad is empty. However, all the comic covers are at least present in the local database on the SYN under .yacreaderlibrary.

I'm not very familiar with Docker and have read about access rights issues. How can I perform a write permission test from within the Docker image?

Did you add your library using yacreaderlibraryserver? You need to use the console to add it.

Hi Luis,

I've created a new libray with this command in the container bash:
YACReaderLibraryServer create-library Ebooks /Ebooks

Trying to add with add-library this was prompted:
A Library named "Ebooks" already exists in the database

Luis Ángel wrote: Did you add your library using yacreaderlibraryserver? You need to use the console to add it.

I forgot to mention that I did a fresh installation with just a few comics.

I created a new directory from within the SYN, copied a few comics into it, and then created a new database on the bash.

But as I said, the new database is empty on the iPad. It connects correctly, the port is right, but no comics are visible.

Even via the web interface on my PC, only the library name is visible, but still no comics.

When the server starts it runs some diagnostics. What do you see in the logs?

Here is the log. I'm wondering about > STATUS: "WARNING! Library does not exist on disk"
Directory is there and I have created the database.
Any suggessions?

By the way, I have another Synology and I build YACReader there from the ground. The same behaviour there.

If I start my old Muallin container everything works fine. 7z error included

2025/12/20 12:57:05 stdout [ls.io-init] done.
2025/12/20 12:57:05 stdout Connection to localhost (::1) 8080 port [tcp/*] succeeded!
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 3 more network interfaces detected
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "███████████████████████████████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "███████████████████████████████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "█████▄▄▄▄▄▄▄█▄███▄█▄█▄█▄███████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "█████ █▄▄▄█ █▄█▄█▄ ▄▀▄█▀█████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "█████ █ █ █ ▀ █ ▄▄█▀▄█▄█████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "█████ ▄▄▄▄▄ █▀█▄█▀ █ ██ ▀▄█████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "███████▄▄▄█▄█ ▄██ ███▀█▄███████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "███████ █▀▄ ██▀█ ▀▄ █▄ ▀█████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "█████▄█▄▄▄▄▄█▀█ █ █▄▄ ▄ █▀█████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "█████▄▄▄▄▄▄▄█ █▄█ █▄▄▄▄▄▄▄█████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "█████ █▄▄▄█ █ ▄▄█ █ █▄▄▄█ █████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "█████ █ █ █ ▄▀██ █ █ █████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "█████ ▄▄▄▄▄ ██▀▄▄▀█ ▄▄▄▄▄ █████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "███████████████████████████████"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 "███████████████████████████████"
2025/12/20 12:57:04 stdout
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.773 Running on "192.168.178.23:8080"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 YACReaderLibrary starting
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772

---

2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 > STATUS: "WARNING! Library does not exist on disk"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "LibraryName [1, cff24011-4827-43c0-a6f9-359060ea59ac, /Ebooks]"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 Libraries:
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 ""
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "PDF support: Poppler"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "Compression backend: 7zip"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "SQLite driver available: yes"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "Image formats supported: bmp, cur, gif, icns, ico, jpeg, jpg, mng, pbm, pgm, png, ppm, tga, tif, tiff, wbmp, webp, xbm, xpm"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "APP INFORMATION"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 ""
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "Product info: Ubuntu 24.04.3 LTS"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "Kernel version: 4.4.302+"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "Kernel type: linux"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "CPU architecture: x86_64"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "build CPU architecture: x86_64"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "Build ABI: x86_64-little_endian-lp64"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "Qt version: 6.4.2"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.772 "SYSTEM INFORMATION"
2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.769

---

System & configuration

---

2025/12/20 12:57:04 stdout INFO 2025-12-20T11:57:04.769 YACReaderLibraryServer attempting to start
2025/12/20 12:57:04 stdout [custom-init] No custom files found, skipping...
2025/12/20 12:57:04 stdout
2025/12/20 12:57:04 stdout

---

2025/12/20 12:57:04 stdout User gid: 911
2025/12/20 12:57:04 stdout User uid: 911
2025/12/20 12:57:04 stdout
2025/12/20 12:57:04 stdout

---

2025/12/20 12:57:04 stdout GID/UID
2025/12/20 12:57:04 stdout

---

2025/12/20 12:57:04 stdout
2025/12/20 12:57:04 stdout |_/_/ \_\_____|_| \_\___|\__,_|\__,_|\___|_|
2025/12/20 12:57:04 stdout | |/ ____ \ |____| | \ \ __/ (_| | (_| | __/ |
2025/12/20 12:57:04 stdout \ // /\ \| | | _ // _ \/ _` |/ _` |/ _ \ __|
2025/12/20 12:57:04 stdout \ \_/ // \ | | | |__) |___ __ _ __| | ___ _ __
2025/12/20 12:57:04 stdout \ \ / //\ / ____| __ \ | |
2025/12/20 12:57:04 stdout __ __ _____ _____ _
2025/12/20 12:57:04 stdout

---

2025/12/20 12:57:04 stdout
2025/12/20 12:57:04 stdout usermod: no changes
2025/12/20 12:57:04 stdout [migrations] no migrations found
2025/12/20 12:57:04 stdout [migrations] started

I think there is something wrong in how the disk content is mapped into the container.

You need to think about a Docker container as a computer running inside a computer. The container has its own disk, if you want it to see the content of the host you need to map a path in the host to a path in the container.

e.g. /MyDocuments/BooksAndComics/Comics -> /comics

/MyDocuments/BooksAndComics/Comics would be the path in the host, where your comics actually are. And /comics would be the path inside the container, where yacreaderlibraryserver can actually see them. So when you add the library, you need to use /comics and not /MyDocuments/BooksAndComics/Comics

I agree Luis.
At the Muallin Image everything works with path, library and database.

I just duplicated your YACReaderLibray image again and tried other variables.
Unfortunately the same, empty database at web and ipad.
Atleast the error with not existing library is gone.
Here is the logfile:
2025/12/20 18:06:47 stdout WARN 2025-12-20T17:06:47.102 QSqlQuery::prepare: database not open
2025/12/20 18:06:47 stdout WARN 2025-12-20T17:06:47.084 QSqlQuery::prepare: database not open
2025/12/20 18:06:47 stdout WARN 2025-12-20T17:06:47.084 QSqlQuery::prepare: database not open
2025/12/20 18:06:46 stdout WARN 2025-12-20T17:06:46.396 QSqlQuery::prepare: database not open
2025/12/20 18:06:46 stdout WARN 2025-12-20T17:06:46.376 QSqlQuery::prepare: database not open
2025/12/20 18:06:46 stdout WARN 2025-12-20T17:06:46.376 QSqlQuery::prepare: database not open
2025/12/20 18:06:44 stdout WARN 2025-12-20T17:06:44.465 QSqlQuery::prepare: database not open
2025/12/20 18:06:44 stdout WARN 2025-12-20T17:06:44.450 QSqlQuery::prepare: database not open
2025/12/20 18:06:44 stdout WARN 2025-12-20T17:06:44.444 QSqlQuery::prepare: database not open
2025/12/20 18:06:44 stdout WARN 2025-12-20T17:06:44.444 QSqlQuery::prepare: database not open
2025/12/20 18:06:41 stdout WARN 2025-12-20T17:06:41.272 QSqlQuery::prepare: database not open
2025/12/20 18:06:41 stdout WARN 2025-12-20T17:06:41.257 QSqlQuery::prepare: database not open
2025/12/20 18:06:41 stdout WARN 2025-12-20T17:06:41.246 QSqlQuery::prepare: database not open
2025/12/20 18:06:41 stdout WARN 2025-12-20T17:06:41.246 QSqlQuery::prepare: database not open
2025/12/20 18:02:19 stdout [ls.io-init] done.
2025/12/20 18:02:19 stdout Connection to localhost (::1) 8080 port [tcp/*] succeeded!
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 3 more network interfaces detected
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "███████████████████████████████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "███████████████████████████████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "█████▄▄▄▄▄▄▄█▄▄▄██▄▄▄███▄██████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "█████ █▄▄▄█ █▄▄ ▀ ▄▄▄█ ███████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "█████ █ █ █▀▄▀▄█▄▀▀▀ ▀▀██████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "█████ ▄▄▄▄▄ █ ▀ █ ▄▄▀▄█▀ ▄█████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "███████▄▄▄█▄█▀█ ▀▄█▀▀▀▀ █▀█████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "█████▄▀ ▄▀▄▄ █▀▄████▀██▄ █████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "█████▄▀▄▄▀ ▄▄▀▄ █▀█▄█▀▄▀▄ █████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "█████▄▄▄▄▄▄▄█ ▀▄▀▄█▄▄▄▄▄▄▄█████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "█████ █▄▄▄█ ██▄▀▄██ █▄▄▄█ █████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "█████ █ █ █▀▀▀▄▄█ █ █ █████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "█████ ▄▄▄▄▄ █ ▀▀▀▀█ ▄▄▄▄▄ █████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "███████████████████████████████"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.843 "███████████████████████████████"
2025/12/20 18:02:18 stdout
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.842 Running on "192.168.178.38:8080"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841 YACReaderLibrary starting
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841

---

2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841 Libraries:
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841 ""
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841 "PDF support: Poppler"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841 "Compression backend: 7zip"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841 "SQLite driver available: yes"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841 "Image formats supported: bmp, cur, gif, icns, ico, jpeg, jpg, mng, pbm, pgm, png, ppm, tga, tif, tiff, wbmp, webp, xbm, xpm"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841 "APP INFORMATION"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841 ""
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841 "Product info: Ubuntu 24.04.3 LTS"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841 "Kernel version: 4.4.302+"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841 "Kernel type: linux"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.841 "CPU architecture: x86_64"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.840 "build CPU architecture: x86_64"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.840 "Build ABI: x86_64-little_endian-lp64"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.840 "Qt version: 6.4.2"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.840 "SYSTEM INFORMATION"
2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.697

---

System & configuration

---

2025/12/20 18:02:18 stdout INFO 2025-12-20T17:02:18.697 YACReaderLibraryServer attempting to start
2025/12/20 18:02:17 stdout [custom-init] No custom files found, skipping...
2025/12/20 18:02:17 stdout
2025/12/20 18:02:17 stdout

---

2025/12/20 18:02:17 stdout User gid: 911
2025/12/20 18:02:17 stdout User uid: 911
2025/12/20 18:02:17 stdout
2025/12/20 18:02:17 stdout

---

2025/12/20 18:02:17 stdout GID/UID
2025/12/20 18:02:17 stdout

---

2025/12/20 18:02:17 stdout
2025/12/20 18:02:17 stdout |_/_/ \_\_____|_| \_\___|\__,_|\__,_|\___|_|
2025/12/20 18:02:17 stdout | |/ ____ \ |____| | \ \ __/ (_| | (_| | __/ |
2025/12/20 18:02:17 stdout \ // /\ \| | | _ // _ \/ _` |/ _` |/ _ \ __|
2025/12/20 18:02:17 stdout \ \_/ // \ | | | |__) |___ __ _ __| | ___ _ __
2025/12/20 18:02:17 stdout \ \ / //\ / ____| __ \ | |
2025/12/20 18:02:17 stdout __ __ _____ _____ _
2025/12/20 18:02:17 stdout

---

2025/12/20 18:02:17 stdout

It could be a permissions issue,

2025/12/20 18:02:17 stdout User gid: 911
2025/12/20 18:02:17 stdout User uid: 911

setting the right gid and uid is critical

Luis Ángel wrote: It could be a permissions issue,

2025/12/20 18:02:17 stdout User gid: 911
2025/12/20 18:02:17 stdout User uid: 911

setting the right gid and uid is critical

I totaly agree. But which is the right gid/uid? Muallin doesn't use uid/pid. This 911 is only in your image. I used a script to find out the uid/gid of the main user under which I did the YACServer installation on SYN.
To use them, I had to use the PUID and PGID variables when creating the container.
Now I get this error message on the iPad:
Error The data couldn't be read because it isn't in the correct format.

I don't know any more advice