What causes "Failed to init query tracker db: {}" in dmtrKovalenko/fff?

Verify the history_db_path directory exists and is writable.

Failed to init query tracker db

Error message

Failed to init query tracker db: {}

What it means

QueryTracker::open failed to open or create the LMDB query history database at history_db_path, with the underlying LMDB error embedded in the message. The query history db records previous searches, so without it instance creation fails when history is requested.

Solutions

Verify the history_db_path directory exists and is writable.
Remove corrupted LMDB files (data.mdb/lock.mdb) at that path; history is rebuildable.
Ensure no other process holds an exclusive LMDB lock on the same path.
Choose a different, writable history_db_path to confirm the cause.
Free disk space if the disk is full.

Example fix

// before
opts.history_db_path = "/mnt/ro-vol/fff/history";
// after
opts.history_db_path = "/home/me/.cache/fff/history";

Defensive patterns

Strategy: fallback

Validate before calling

const fs = require('fs');
if (historyPath) { fs.mkdirSync(path.dirname(historyPath), { recursive: true }); fs.accessSync(path.dirname(historyPath), fs.constants.W_OK); }

Try / catch

try {
  createInstance({ ...opts, history_db_path: p });
} catch (e) {
  if (/Failed to init query tracker db/.test(e.message)) {
    fs.rmSync(p, { recursive: true, force: true }); // drop corrupt history db
    return createInstance({ ...opts, history_db_path: p });
  }
  throw e;
}

Prevention

Store history in a writable user cache directory.
Avoid sharing a single history path across processes or versions.
Recreate the db freely on corruption; it is non-critical data.
Check for lock holders and disk space before blaming permissions.

When it happens

Trigger: history_db_path in an unwritable or non-existent location; corrupted/locked LMDB files; disk full; invalid path characters on the platform.

Common situations: Read-only cache dirs in CI/containers; corrupted db after an abrupt kill; two apps sharing one history path with incompatible versions; permission errors after user change.

Understand the failure class

Background: Database query failed: Internal Server Error 500s wrapping SQL, Prisma, and connection failures — what to check first — this error's family across 16 libraries.

Related errors

AI-assisted analysis of dmtrKovalenko/fff@7f8537e70f (2026-09-10). Data as JSON: /api/errors/92b40e050451a9a9. Report an issue: GitHub.

Appendix: source

Thrown at crates/fff-c/src/lib.rs:240

                    return FffResult::err(&format!("Failed to acquire frecency lock: {}", e));
                }
            }
            Err(e) => return FffResult::err(&format!("Failed to init frecency db: {}", e)),
        }
    }

    if let Some(ref history_path) = history_path {
        if let Some(parent) = PathBuf::from(history_path).parent() {
            let _ = std::fs::create_dir_all(parent);
        }

        match QueryTracker::open(history_path) {
            Ok(tracker) => {
                if let Err(e) = query_tracker.init(tracker) {
                    return FffResult::err(&format!("Failed to acquire query tracker lock: {}", e));
                }
            }
            Err(e) => return FffResult::err(&format!("Failed to init query tracker db: {}", e)),
        }
    }

    let mode = if opts.ai_mode {
        FFFMode::Ai
    } else {
        FFFMode::Neovim
    };

    let cache_budget = fff::ContentCacheBudget::from_overrides(
        opts.cache_budget_max_files as usize,
        opts.cache_budget_max_bytes,
        opts.cache_budget_max_file_size,
    );

    if let Err(e) = FilePicker::new_with_shared_state(
        shared_picker.clone(),
        shared_frecency.clone(),

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