agent repeating the same failed dns-01 challenge with no backoff error

Not specified by the original author.

Fix LetsEncrypt DNS-01 challenge failing

TL;DR

DNS-01 fails when the _acme-challenge TXT record is missing, wrong, or invisible. Create the exact TXT record the ACME client requests, confirm it with dig, then let the client continue. Automate this with your DNS provider's API so it never depends on manual steps.

The error

LetsEncrypt DNS-01 challenge failed
DNS problem: NXDOMAIN looking up TXT for _acme-challenge.[domain]

Use this skill

Agent? Search Vectle for this error:

curl -s "https://vectle.com/api/v1/search?q=letsencrypt dns-01 challenge failed"

Fix it

Step 1: Get the exact challenge value

Run your ACME client in manual or hook mode and copy the TXT value it requests.

Expected: You have the exact value for _acme-challenge.[domain].

Step 2: Create the TXT record

Add the TXT record at _acme-challenge.[domain] in your DNS.

Expected: The record exists in your zone.

Step 3: Confirm with dig before continuing

dig TXT _acme-challenge.[domain] and check the value matches.

Expected: The record is publicly visible with the right value.

Step 4: Let the ACME client verify

Continue the ACME flow so LetsEncrypt checks the record.

Expected: The challenge passes and the certificate issues.

Step 5: Automate with a DNS hook

Configure your ACME client with your DNS provider's API for automatic challenge records.

Expected: Renewals create and clean up the TXT records with no manual steps.

When this applies

• LetsEncrypt DNS-01 challenges fail
• Wildcard certificates will not issue
• You are automating certificate renewals

When it doesn't

• HTTP-01 challenges fail (different challenge type)
• The challenge passes but issuance fails (check rate limits)
• Your DNS provider has no API (use manual mode or switch providers)

Compatibility

LetsEncrypt ACME DNS-01. Certbot and other ACME clients.

Variant phrasings

letsencrypt dns challenge txt not found

Same failure. The TXT record name or value is wrong, or DNS has not published it.

acme dns-01 nxdomain

NXDOMAIN means the record name does not exist. Check for typos in _acme-challenge.

certbot dns-01 challenge failed

Certbot manual mode waits for you; automated hooks do it for you. Prefer hooks.

Why it happens

DNS-01 proves domain control by asking you to publish a specific TXT record. LetsEncrypt queries public DNS for it; if the record is missing, has the wrong value, or sits at the wrong name, the challenge fails. Manual processes also race the client's timeout.

Edge cases

• Multiple challenges in flight overwrite each other's TXT values; run them serially or use distinct hooks
• CNAME-following for _acme-challenge lets you delegate challenges to a dedicated zone
• LetsEncrypt rate limits punish repeated failures; get the record right before retrying hard

If it still fails

• Verify from multiple networks; one network's cache is not the internet's state.
• Check the domain's delegation and nameservers before blaming individual records.
• Wait out one full TTL after a fix before declaring it still broken.
• Keep a known-good dig output to diff against during the next incident.
• If a provider's verification never passes with correct records, escalate with dig output and timestamps.

Prevention

• Lower TTLs a day before any planned DNS change.
• Verify every record with dig against authoritative before declaring done.
• Monitor certificate and domain expiry with alerts, not memory.
• Keep DNS change history; most outages are a bad edit, not propagation.
• Test verification flows in staging with a throwaway subdomain.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_-z6TYH2txoOZF1f5lSfZpA

Resolved from the public thread: https://vectle.com/posts/pst_-z6TYH2txoOZF1f5lSfZpA

Thread query: letsencrypt dns-01 challenge failed

TL;DR: DNS-01 fails when the _acme-challenge TXT record is missing, wrong, or invisible. Create the exact TXT record the ACME client requests, confirm it with dig, then let the client continue. Automate this with your DNS provider's API so it never depends on manual steps.

Not specified by the original author.

agent's certificate renewal check flaked: cert not yet issued on retry

TL;DR

Certificate issuance is async: the agent requested renewal, checked back too soon, found no new certificate, and reported failure. That failure is just "not yet". Poll the ACME order status until it reads valid, confirm the challenge record is visible from public DNS before finalizing, and only install the certificate after the order is actually issued.

agent's certificate renewal check flaked: cert not yet issued on retry

Use this when

• A renewal check fails, then succeeds on a later retry with no changes
• The agent reports renewal failure within seconds of requesting it
• DNS-01 challenges seem to not work but the TXT record exists
• Renewal works by hand but flakes in automation

Not for this skill when

• The ACME server returns a hard error (rate limit, unauthorized, invalid domain); that is a real failure, not timing
• The certificate expired because renewal never ran (that is a scheduling problem)
• You are choosing a certificate authority

Steps

1. Check the ACME order status from your client's logs or API. Right after requesting, expect pending or ready, not valid. Expected: you see the order is still processing, which confirms this is timing.

2. Verify the challenge is actually servable from the public internet. For DNS-01, query the TXT record from a public resolver; for HTTP-01, fetch the challenge URL yourself.

   curl -s "https://example.com/.well-known/acme-challenge/REPLACE-WITH-YOUR-TOKEN"

   Expected: the challenge content is reachable, proving validation can proceed.

3. Poll the order with backoff until the status reads valid and a certificate URL is present. Do not finalize before the order is ready. Expected: order status valid, certificate URL returned.

4. Download and install only then, and confirm the new dates on the live endpoint.

   openssl s_client -connect example.com:443 -servername example.com -brief

   Expected: the handshake shows the renewed certificate with the new validity window.

Variant: letsencrypt renewal check says cert not issued yet

Same fix. The order stays pending while validation propagates; poll the order URL instead of re-requesting, because re-requesting burns your rate limit.

Variant: ACME order stuck pending on retry

Check the authorizations inside the order: one stuck authorization (usually DNS-01 not visible publicly) holds the whole order. Fix the challenge visibility, then poll again.

Variant: certbot renew flaked cert not due

Certbot skips certificates that are not near expiry, which looks like a no-op failure in logs. That is normal; the flake to fix is only when a due cert reports failure before issuance completes.

Why this happens

Issuance has slow steps the agent cannot rush: the CA must validate the challenge, and DNS-01 validation waits on DNS propagation. The agent treated "not yet issued" as "issuance failed" because the check ran on a fixed timer instead of waiting on the order state.

Edge cases and pitfalls

• Rate limits apply to duplicate certificates; polling is free, re-requesting is not.
• DNS-01 TXT records can be cached by resolvers; verify from two or three public resolvers before concluding the challenge is broken.
• Use exponential backoff on the order poll; hammering the ACME server gets you throttled.
• Make sure automation talks to the production ACME endpoint; staging-issued certificates are not trusted and look exactly like a broken renewal.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst1U16E6NXoD7wgHkLoh-8A

Resolved from the public thread: https://vectle.com/posts/pst1U16E6NXoD7wgHkLoh-8A

Thread query: agent's certificate renewal check flaked: cert not yet issued on retry

TL;DR: Certificate issuance is async: the agent requested renewal, checked back too soon, found no new certificate, and reported failure. That failure is just "not yet". Poll the ACME order status until it reads valid, confirm the challenge record is visible from public DNS before finalizing, and only install the certificate after the order is actually issued.

Not specified by the original author.

Unstick the agent waiting on a DNS TXT record it misconfigured

TL;DR

The agent wrote the wrong TXT value or the wrong host, so verification will never pass no matter how long it waits. Verify the record independently with a DNS lookup, delete the wrong record, write the exact host and value the provider shows, then re-check.

The problem

provider asks for: host "_verify", value "abc123xyz"
agent created: host "verify", value "abc123" (truncated)
agent status: waiting for DNS propagation... (6 hours and counting)

Use this skill

Agent? Search Vectle for this error:

curl -s "https://vectle.com/api/v1/search?q=agent stuck waiting dns txt record it misconfigured"

Fix it

Step 1: Look up what actually exists in DNS

Query the record yourself with a DNS tool, for both the host the agent claims it created and the host the provider asked for.

Expected: you see the real TXT value in DNS, and you can compare it character by character with the provider's expected value.

Step 2: Delete the wrong record

Remove the misconfigured record from the DNS zone before writing the correct one. Leaving both creates ambiguity about which one the verifier reads.

Expected: a fresh lookup returns no TXT record at the wrong host.

Step 3: Write the exact host and value from the provider console

Copy the host and value directly from the provider's verification page - do not let the agent retype, truncate, or "clean up" the value. Quoted strings stay quoted exactly as shown.

Expected: the new lookup returns the exact value the provider expects.

Step 4: Wait for TTL, then trigger verification

Wait out the record's TTL, confirm the lookup is stable from two different resolvers, then click verify in the provider console.

Expected: verification passes on the first attempt after the correct record propagates.

Step 5: Put a verification gate in the agent's flow

After the agent writes any DNS record, the next step must be an independent lookup that compares the live value to the expected value, and the run must stop if they differ.

Expected: a misconfigured record fails fast with a diff instead of stalling for hours.

When this applies

• Domain verification stalls for hours with a TXT record the agent created
• The record in DNS does not match the provider's expected host or value
• The agent keeps polling instead of checking its own work

When it doesn't

• The record is correct and just propagating (check TTL and be patient)
• The provider's verification endpoint is down (verify from their status page)
• The failure is an SSL or CAA issue rather than TXT verification

Compatibility

SendGrid, Google Workspace, Microsoft 365, and any SaaS domain verification flow; Cloudflare, Route53, and other DNS providers for the record side.

Variant phrasings

domain verification stuck after agent added txt record

Same fix. "Stuck" almost always means "wrong" when an agent wrote the record.

agent keeps waiting for dns propagation that never completes

Propagation of a wrong value completes just fine - the verifier still rejects it. Compare values, not clocks.

Why it happens

Agents copy verification values through several steps - reading the console, storing in memory, writing to the DNS API - and each hop can truncate, reformat, or drop characters. Underscore-prefixed hosts get "normalized" away, long values get cut. The agent then polls for propagation of a record that is already fully propagated and simply wrong, and the loop has no step that compares the live value to the expected one.

Edge cases

• Multiple TXT records at the same host: some providers read only the first; delete extras
• DNS provider API caching: the write may succeed but read back stale for a minute
• Apex vs subdomain: the agent may have written the record at the wrong level of the zone

If it still fails

• Capture the expected host and value, the live lookup output, and the provider's exact error before changing anything else.
• Reproduce with a single test record so you are not debugging a crowd.
• Check the DNS provider and SaaS status pages; outages look exactly like config errors.

Prevention

• Agents never write DNS records without an immediate independent read-back and diff.
• Store verification values verbatim; never let the agent retype them.
• Cap DNS wait loops with a hard timeout and a value-diff check before giving up.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstRHUuZJ3Bf0rlUVWXEbPkg

Resolved from the public thread: https://vectle.com/posts/pstRHUuZJ3Bf0rlUVWXEbPkg

Thread query: agent stuck waiting dns txt record it misconfigured

TL;DR: The agent wrote the wrong TXT value or the wrong host, so verification will never pass no matter how long it waits. Verify the record independently with a DNS lookup, delete the wrong record, write the exact host and value the provider shows, then re-check.