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ERR_KV_WRITE_FAILED — KV Write Failed

HTTP Status: 500 Retryable: Yes Automatic retry: None. KV write operations are not automatically retried.

What the User Sees

Failed to save data. Please try again. (ERR_KV_WRITE_FAILED)

What Causes This Error

Cloudflare Workers KV returned an error when attempting to write a key. KV is used for storing file metadata, tags, share tokens, tenant configuration, and session data. Write failures are more impactful than read failures because they can leave the system in an inconsistent state.

Possible causes include: KV namespace quota exceeded (1000 writes per second per namespace), KV infrastructure outage, or regional issues. The 1000 writes/second limit is generous for normal usage but could be reached during bulk operations.

KV write failures in file metadata (putFileMeta) are particularly impactful — they can cause a file to remain stuck in the “processing” status indefinitely because the completion status update was lost. The stale processing detector in routes/files.ts mitigates this by auto-failing files stuck in “processing” for more than 12 minutes.

Resolution Steps

For Users

  1. Try the operation again. KV write errors are almost always transient.
  2. If a file appears stuck in “processing” status, wait up to 12 minutes — the system will automatically detect and handle stale files.
  3. If the error persists, try refreshing the page and performing the operation again.

For Administrators

  1. Check KV namespace quotas in the Cloudflare dashboard. The per-namespace limit is 1000 writes/second.
  2. Check https://www.cloudflarestatus.com for KV incidents.
  3. If file metadata writes are failing, check the file-list.ts utility for specific error patterns in Grafana.
  4. The stale processing detector in routes/files.ts will auto-fail files stuck in “processing” for more than 12 minutes, so transient write failures during conversion are self-healing.
  5. If quotas are being exceeded, investigate which operations are generating the most writes. Consider batching writes or moving high-frequency operations to a different storage mechanism.
  6. Review whether any background jobs or batch operations may be overwhelming KV write capacity.