Before you upgrade

Most updates need nothing from you. An update installs over the version you have, and your library and settings stay as they are.

Make a backup before any update anyway: More→Data and storage, then Create backup. Backups covers what a backup holds and how to restore one.

The cases below are the ones that need extra steps or bring a change you should know about.

From Reikai 0.3.2

Back up first. The upgrade itself needs no steps, but it changes some of your data:

• A manga or novel you have twice from the same source becomes one, keeping the library copy with your read chapters, history, categories, tracking, custom cover and downloads.
• Your novel library takes on the manga library's sort, filters and grouping, and existing categories carry over as Manga only or Novels only.
• Novels open in the shared reader, and a chapter you have already read opens at its start unless Resume reading position is on in More→Settings→Novel reader.

Novels an earlier build saved with another novel's title and cover, or wrongly as Completed, stay that way until you refresh them. Repair novel details, in More→Settings→Advanced, finds the library novels showing another novel's title and cover and re-fetches them in one pass; refresh any it misses by hand.

From Reikai 0.3.1 or older

Reikai 0.3.2 changed the ID Android uses to recognise the app. Android treats it as a different app, so 0.3.2 and later install next to an older Reikai rather than over it, and nothing moves across on its own.

1. In the old app, go to More→Data and storage and tap Create backup. Tick Include sensitive settings so your tracker logins come along.
2. Install the new Reikai.
3. When it asks for a storage location, pick the same folder the old app used, so your downloads are found.
4. Restore the backup in the new app, from More→Data and storage.
5. Check your library, then uninstall the old app.

Covers you set from an image on your device are not in a backup, so set those again.

From Yōkai, Yōkai-Y2K or another fork

Reikai reads backups from Mihon and the forks it lists, so you move across by backing up in the old app and restoring that file in Reikai. That covers Mihon itself and TachiyomiJ2K, TachiyomiSY, TachiyomiAZ, Yōkai and Komikku. Yōkai-Y2K and older Yōkai-based Reikai builds use the same format.

1. In the old app, create a backup. A .tachibk or .proto.gz file works.
2. Install Reikai. It installs as a separate app, so the old one stays until you remove it.
3. Restore the backup from More→Data and storage.
4. Install the extensions the Restore screen lists, and log in to your trackers again unless the backup included your sign-ins.

What comes across: your library, categories, reading history and tracking links.

What does not:

• An old .json backup from TachiyomiAZ does not restore.
• Settings specific to the app that wrote the file. Each fork saves its own extras next to the shared data, and an app without that feature ignores them.
• From a Yōkai backup, a default category or library update categories other than Default are left for you to pick again, since Yōkai saves no way to match them to your categories.
• Details you edited yourself come across from Komikku and Yōkai, except an edited cover address, which Yōkai does not keep.

Not every fork has been tested, so check the other app's own docs too.

Going back the other way

A backup made in Reikai restores in Mihon and the forks above with your manga only. Your light novels are saved in a part of the file those apps do not read.

Reikai 0.3.2 and older restore a backup made by this version without the details you edited yourself.