ruvnet/ruflo · error

Invalid KV cache magic: 0x

Error message

Invalid KV cache magic: 0x${magic.toString(16)}

What it means

The first u32 of an RVF KV cache file must equal RVKV_MAGIC (0x564B5652, ASCII 'RVKV' little-endian); a different value throws. The bytes at inputPath are not an RVF KV cache — typically a model file or unrelated binary/text data passed as a cache.

Solutions

1. Ensure loadKvCache only receives files produced by persistKvCache
2. Check the first 4 bytes read 'RVKV' before loading; otherwise regenerate the cache
3. Keep caches in a dedicated directory with a distinctive extension so they cannot be confused with models

const fh = await open(cachePath, 'r');
const b = Buffer.alloc(4);
await fh.read(b, 0, 4, 0); await fh.close();
if (b.toString('ascii') !== 'RVKV') throw new Error('not an RVF KV cache');
await engine.loadKvCache(cachePath);

async function isRvkvCache(path: string): Promise<boolean> {
  const fh = await open(path, 'r');
  const b = Buffer.alloc(4);
  const { bytesRead } = await fh.read(b, 0, 4, 0);
  await fh.close();
  return bytesRead === 4 && b.toString('ascii') === 'RVKV';
}

try { await engine.loadKvCache(cachePath); }
catch (e) { if (e instanceof Error && e.message.includes('Invalid KV cache magic')) { await engine.persistKvCache(cachePath); } else throw e; }

When it happens

Trigger: loadKvCache(modelPath) where a .gguf model was given as the cache path; a cache directory shared with another engine's format; a corrupted or empty-but-sized file.

Common situations: Config wiring that swaps model and cache path values; caches from a different appliance version using another format; leftover files with the same extension.

Related errors

• Invalid GGUF magic: 0x
• Unsupported KV cache version
• Invalid RVFA magic: expected "RVFA", got
• KV cache file too small
• KV cache file truncated

AI-assisted analysis of ruvnet/ruflo@fa13ee4ad6 (2026-08-18). Data as JSON: /api/errors/705f5458d8beebc2. Report an issue: GitHub.

Appendix: source

Thrown at v3/@claude-flow/cli/src/appliance/gguf-engine.ts:392

    const footer = createHash('sha256').update(entryData).digest();

    const header = Buffer.alloc(44);
    header.writeUInt32LE(RVKV_MAGIC, 0);
    header.writeUInt32LE(RVKV_VERSION, 4);
    modelHash.copy(header, 8);
    header.writeUInt32LE(this.kvCache.size, 40);

    await writeFile(path, Buffer.concat([header, entryData, footer]));
    if (this.config.verbose) console.log(`[gguf-engine] KV cache persisted: ${this.kvCache.size} entries`);
  }

  /** Restore KV cache from an RVF-compatible binary file. */
  async loadKvCache(inputPath: string): Promise<void> {
    const data = await readFile(inputPath);
    if (data.length < 44) throw new Error('KV cache file too small');

    const magic = data.readUInt32LE(0);
    if (magic !== RVKV_MAGIC) throw new Error(`Invalid KV cache magic: 0x${magic.toString(16)}`);
    const version = data.readUInt32LE(4);
    if (version !== RVKV_VERSION) throw new Error(`Unsupported KV cache version: ${version}`);

    const entryCount = data.readUInt32LE(40);
    let offset = 44;
    const entries = new Map<string, Buffer>();

    for (let i = 0; i < entryCount; i++) {
      if (offset + 8 > data.length) throw new Error('KV cache file truncated');
      const keyLen = data.readUInt32LE(offset);
      const valLen = data.readUInt32LE(offset + 4);
      offset += 8;
      if (offset + keyLen + valLen > data.length) throw new Error('KV cache file truncated');
      entries.set(data.toString('utf-8', offset, offset + keyLen), Buffer.from(data.subarray(offset + keyLen, offset + keyLen + valLen)));
      offset += keyLen + valLen;
    }

    // Verify footer hash (mandatory)

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