# Frequently Asked Questions

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

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.