# Frequently Asked Questions

# Migration from H2 to SQLite

The version 0.48.0 is changing the internal database from H2 to SQLite. The change is done transparently.

A migration will be triggered automatically at startup:

  • if the H2 database has not been migrated yet
  • if the SQLite database is newly created

The regular functions of Komga will not be available during the data transfer (API, webserver, library scan…).

After a successful migration, a file with the .imported extension will be created next to your existing H2 database (for example for the default configuration it would be ~/.komga/database.h2.mv.db.imported).

By default, the SQLite database will be located in the same location as the H2 database:

  • if using the Jar: ~/.komga/database.sqlite
  • if using Docker: /config/database.sqlite

You can customize the location of the SQLite database using the configuration komga.database.file or environment variable KOMGA_DATABASE_FILE.

The database backup feature introduced in 0.37.0 has been removed. It might be re-added later on using a different logic.

# Komga doesn't start, logs show error message about the database

TIP

Migrate to 0.48.0 to avoid those issues!

If Komga does not start, and you have this kind of error messages in the logs:

org.h2.jdbc.JdbcSQLNonTransientException: General error: "java.lang.IllegalStateException: Chunk 20221 not found [1.4.200/9]" [50000-200]

It means the database is corrupt, and you need to restore from a backup.

Since 0.37.0 Komga has automatic database backups enabled by default. You will find a database-backup.zip file in ~/.komga/ (for jar) or /config/ (for docker).

  1. Make sure Komga is stopped
  2. Delete the corrupt database (database.h2.mv.db)
  3. Unzip database-backup.zip, it should contain a database.h2.mv.db file
  4. Restart Komga

# Media type application/x-7z-compressed is not supported

Your files are compressed using 7zip, which is not supported. Extract your archives and compress them again using the zip format.

# ChunkyTNG displays the wrong number for my books

ChunkyTNG is doing a lot of caching, you may need to remove/add your OPDS server to force ChunkyTNG to update.

# My books/series show a different name than the files/folders

Komga automatically import metadata from EPUB files and from ComicInfo.xml for cbz/cbr. The imported metadata will override the file/folder name.

# This server has already been claimed

The server cannot be claimed if a user already exists in the database. It can happen when you start Komga for the first time without the claim profile as Komga will generate a default user.

You can solve the issue by deleting the database. By default it is located in ~/.komga/database.h2. ~ is your home directory on Unix, and your User profile on Windows.

# Tachiyomi does not show thumbnails

Make sure the URL of your Komga server starts with http or https in lowercase.

# How can I disable the periodic scans?

Configure KOMGA_LIBRARIES_SCAN_CRON / komga.libraries-scan-cron to -.