Where Does Hydrus Network Store Its Database?
Where Hydrus keeps its database, media files and how to move them.
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Hydrus is fully portable: the install folder holds the executables while install_dir/db holds SQLite files (client.db and siblings) plus client_files media in hash folders. No settings hide in the OS.
The --db_dir flag relocates the database anywhere, and macOS App builds default to ~/Library/Hydrus instead. Permission failures silently spawn fresh databases in ~/Hydrus, which explains most suddenly empty boots. Check help, about for the live paths.
Where Hydrus Network stores this, by platform
<Hydrus install folder>\db\
Portable database root with SQLite files and hash organized client_files. Override with --db_dir. Fallback ~/Hydrus appears on permission failures. Search client.mappings.db to find lost databases. Back up before every update.
<Hydrus install folder>/db/
Same layout and --db_dir flag on Linux. Keep the database on local SSD storage, never network mounts, since SQLite locking fakes badly over networks. Export folders referenced by absolute path need fixing after moves.
~/Library/Hydrus/
App builds default outside the bundle at ~/Library/Hydrus. Source runs honor --db_dir the same way. Use file, open, database directory in the client to confirm the live location.
Frequently asked questions
Hydrus booted empty. Where is my real database?
Search the system for client.mappings.db, the most distinctive of the four database files. Installing over the old folder with a fresh extract is the classic way empty databases overwrite real ones.
How do I move Hydrus to a new computer?
Install fresh on the new machine, then copy the db folder over and fix any outside paths in the repair dialog. Nothing lives in AppData or the registry, so the install folder plus external file locations are the whole migration.
Notice an outdated path? Let us know.