What causes "Chroma query failed - connection lost: ${errorMessage}" in thedotmack/claude-mem?

Retry the query after a short delay; collectionCreated was reset so the collection/connection is re-established automatically.

thedotmack/claude-mem · error · Error

Chroma query failed - connection lost

Error message

Chroma query failed - connection lost: ${errorMessage}

What it means

ChromaSync.query detects connection-class failures (the error message includes connection-loss indicators such as timeouts) while querying Chroma. It resets collectionCreated so the next call re-creates the collection, logs the failure, and throws a new Error 'Chroma query failed - connection lost: <msg>'. This signals that the Chroma connection must be re-established, not just retried blindly.

Solutions

Retry the query after a short delay; collectionCreated was reset so the collection/connection is re-established automatically.
Verify the Chroma server is running and reachable at the configured host/port.
Add keep-alive or lower idle timeouts on proxies between the app and Chroma.
Catch this error and trigger a re-probe/reconnect before resuming sync.
Increase the query timeout if queries legitimately take longer than the server timeout.

Example fix

// before
const results = await chromaSync.query(project, queryText);
// after
let results;
try {
  results = await chromaSync.query(project, queryText);
} catch (e) {
  if (String(e.message).includes('connection lost')) {
    await sleep(1000);
    results = await chromaSync.query(project, queryText);
  } else throw e;
}

Defensive patterns

Strategy: retry

Validate before calling

// health-check Chroma before heavy query loops
const healthy = await fetch(`${chromaBaseUrl}/api/v1/heartbeat`, { signal: AbortSignal.timeout(3000) }).then(r => r.ok).catch(() => false);
if (!healthy) await reconnectChroma();

Try / catch

try {
  results = await chromaSync.query(project, q);
} catch (e) {
  if (/Chroma query failed - connection lost/.test(e.message)) {
    await sleep(1000); results = await chromaSync.query(project, q); // collection is re-created
  } else throw e;
}

Prevention

Retry with backoff: connection errors are transient after collectionCreated reset
Keep idle keep-alive settings on any proxy between app and Chroma
Set realistic query timeouts so long queries aren't mistaken for connection loss
Probe Chroma heartbeat periodically to detect drops before queries fail

When it happens

Trigger: A query() call against Chroma where the underlying error is a connection drop, socket error, or timeout (errorMessage includes the connection-error markers checked in isConnectionError).

Common situations: Chroma server restarted or OOM-killed mid-session, idle connection reaped by a proxy/load balancer, network partition between app and Chroma, or query exceeding server timeout.

Related errors

AI-assisted analysis of thedotmack/claude-mem@d8bc9755e7 (2026-09-17). Data as JSON: /api/errors/05379f592c572818. Report an issue: GitHub.

Appendix: source

Thrown at src/services/sync/ChromaSync.ts:1106

        n_results: limit,
        ...(whereFilter && { where: whereFilter }),
        include: ['documents', 'metadatas', 'distances']
      });
    } catch (error) {
      const errorMessage = error instanceof Error ? error.message : String(error);

      const isConnectionError =
        errorMessage.includes('ECONNREFUSED') || // [ANTI-PATTERN IGNORED]: ChromaMcpManager.callTool re-wraps transport failures as plain Errors, so the Node error code only survives in the message text; the full error object is logged below.
        errorMessage.includes('ENOTFOUND') || // [ANTI-PATTERN IGNORED]: same MCP transport re-wrapping as above; no structured code field is available on the re-wrapped error.
        errorMessage.includes('fetch failed') || 
        errorMessage.includes('subprocess closed') || 
        errorMessage.includes('timed out'); 

      if (isConnectionError) {
        this.collectionCreated = false;
        logger.error('CHROMA_SYNC', 'Connection lost during query',
          { project: this.project, query }, error as Error);
        throw new Error(`Chroma query failed - connection lost: ${errorMessage}`);
      }

      logger.error('CHROMA_SYNC', 'Query failed', { project: this.project, query }, error as Error);
      throw error;
    }

    return this.deduplicateQueryResults(results);
  }

  private deduplicateQueryResults(results: any): { ids: number[]; distances: number[]; metadatas: any[] } {
    const ids: number[] = [];
    const seen = new Set<string>();
    const docIds = results?.ids?.[0] || [];
    const rawMetadatas = results?.metadatas?.[0] || [];
    const rawDistances = results?.distances?.[0] || [];

    const metadatas: any[] = [];
    const distances: number[] = [];

View on GitHub (pinned to d8bc9755e7)