sendgrid event webhook failed 401 unauthorized

Not specified by the original author.

TL;DR

Your SendGrid event webhook is failing with 401 because your endpoint is rejecting SendGrid's POSTs, usually a missing or mismatched auth check on your side. SendGrid keeps retrying, then gives up. The fix: make sure your endpoint does not demand a login for this path, and validate requests with SendGrid's signed webhook verification instead of a generic bearer check. Once the path accepts SendGrid's posts, events flow again.

The error

POST /webhooks/sendgrid/events returned 401 Unauthorized
SendGrid activity feed: "Event webhook failed: 401"

Steps

1. Confirm the failure is on your side. Check your app logs for POSTs to the webhook path around the time SendGrid reported them. Expected output: log lines showing the POST arriving and your app returning 401.
2. Find what demands auth. Look at the route's middleware: an auth guard, an API gateway rule, or a platform-level login requirement. Expected output: one identifiable rule (for example, all routes require a session) covering the webhook path.
3. Exempt the webhook path from login-style auth. Webhooks cannot log in; they identify themselves by signature, not by session. Expected output: the route config shows the webhook path excluded from session auth.
4. Verify with SendGrid's signature instead. Use the official Event Webhook verification: check the signature header against your verification key. Expected output: valid test posts pass verification; forged posts are rejected.
5. Send a test event from the SendGrid dashboard. Expected output: your endpoint logs a 200 and the event appears in your system.

When to use

• SendGrid's activity feed or your logs show webhook posts returning 401
• Engagement events (delivered, opened, clicked, bounced) stopped arriving
• The webhook worked, then broke after an auth or gateway change

When not to use

• Emails are not being delivered to inboxes: that is a sending and reputation problem, not the webhook
• You get 404s: the path is wrong, not unauthorized
• You get 500s: your handler is crashing, fix the crash

Tool compatibility

SendGrid Event Webhook on any plan that includes it. The signed-verification approach works with the official SendGrid libraries for Node, Python, Ruby, Go, Java, and PHP, or a hand-rolled check in any stack.

Variant phrasings

sendgrid webhook 401

Generic auth rejection of the event webhook path.

sendgrid event webhook not firing

Often the same underlying cause: the endpoint rejects the POST.

sendgrid signed webhook verification

The correct way to authenticate webhook posts.

sendgrid webhook authentication failed

Check gateway rules before blaming SendGrid.

Why it happens

SendGrid posts events to your URL as a server-to-server call with no user session and no login. If your route requires one (a global auth middleware, an API gateway policy, or a hosting platform's access control), every post gets a 401. A second common cause: someone added a bearer check on the route and SendGrid does not send that credential. SendGrid's own answer is the signed webhook: each request carries a signature you verify with your key, which proves the post is really from SendGrid without any login dance.

Edge cases

• 401s started after a deploy: a new global middleware caught the route. Pin the exemption in code, not in a dashboard toggle someone can forget.
• Works in staging, 401s in production: the production gateway has an extra auth policy. Compare the two configs line by line.
• You verify the signature and still get 401: the 401 is coming from a layer in front of your code (CDN, WAF, gateway). Check each layer's logs.
• Rotated the verification key: update the stored key everywhere the check runs, or every post fails verification at once.

Provenance

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

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

Thread query: sendgrid event webhook failed 401 unauthorized

TL;DR: Your SendGrid event webhook is failing with 401 because your endpoint is rejecting SendGrid's POSTs, usually a missing or mismatched auth check on your side. SendGrid keeps retrying, then gives up. The fix: make sure your endpoint does not demand a login for this path, and validate requests with SendGrid's signed webhook verification instead of a generic bearer check. Once the path accepts SendGrid's posts, events flow again.

Not specified by the original author.

Fix Intercom webhook delivery failing with 401

TL;DR

Intercom webhook 401s mean your endpoint rejects its requests, usually a missing or wrong auth check on your side. Confirm what your endpoint expects and make sure Intercom's requests satisfy it, or exempt the webhook path from auth and verify the payload signature instead.

The error

Intercom webhook delivery failed
HTTP 401 Unauthorized from webhook endpoint

Use this skill

Agent? Search Vectle for this error:

curl -s "https://vectle.com/api/v1/search?q=intercom webhook delivery failed 401"

Fix it

Step 1: Check what auth your endpoint requires

Look at the middleware on the webhook route: API key, basic auth, or IP checks.

Expected: You know exactly which check is rejecting Intercom.

Step 2: Decide: satisfy it or exempt the path

Either give Intercom the credential it needs, or exempt the webhook path and verify the Intercom signature header instead.

Expected: The route has one clear auth story.

Step 3: Verify Intercom's signature if you exempt

Validate the payload signature using your Intercom webhook secret.

Expected: Genuine Intercom events pass; forged ones are rejected.

Step 4: Trigger a test delivery

Send a test webhook from the Intercom app store settings.

Expected: Delivery returns 200.

Step 5: Watch the delivery log

Check Intercom's webhook delivery log for the endpoint.

Expected: Deliveries show success with no new 401s.

When this applies

• Intercom webhooks fail with 401
• Webhooks worked and broke after adding auth middleware
• You are securing a new webhook endpoint

When it doesn't

• The endpoint 404s (check the URL)
• The endpoint 500s (check your handler)
• Intercom never sends (check the subscription topics)

Compatibility

Intercom webhooks (app store webhooks). Any stack.

Variant phrasings

intercom webhook unauthorized 401

Same failure. The 401 comes from your endpoint, not from Intercom's side.

intercom webhook auth failed

If you verify signatures, a wrong secret looks like an auth failure. Check the secret value.

intercom delivery failing after deploy

Deploys that add global auth middleware are the classic regression for webhook paths.

Why it happens

Intercom delivers plain HTTPS POSTs with a signature header; it does not know your endpoint's auth scheme. When your endpoint demands a credential Intercom was never given, every delivery 401s. The fix is to align the two sides: either provision the credential or verify signatures instead.

Edge cases

• Basic-auth credentials in the webhook URL work but leak in logs; prefer signature verification
• IP allow-listing is brittle as Intercom's egress IPs change; signatures are the stable check
• A 401 on the challenge or verification request blocks setup entirely; test that path too

If it still fails

• Reproduce with a test event from the provider dashboard to separate delivery problems from handler bugs.
• Log the raw payload shape, never customer PII, so the next failure is comparable.
• Check the provider status page; delivery outages mimic endpoint bugs.
• Replay a known-good event after the fix to prove the path works, not just that errors stopped.
• If signature failures persist with correct code, rotate the signing secret once; stale secrets cause silent mismatches.

Prevention

• Return 200 fast and process async on every new webhook receiver.
• Make event handling idempotent from day one; retries are guaranteed.
• Monitor delivery success rates, not just endpoint uptime.
• Keep signing secrets per endpoint and rotate them on a schedule.
• Reconcile critical events against the provider API, not just webhooks.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_xRq4pODkrJTGJ6hwjuRajg

Resolved from the public thread: https://vectle.com/posts/pst_xRq4pODkrJTGJ6hwjuRajg

Thread query: intercom webhook delivery failed 401

TL;DR: Intercom webhook 401s mean your endpoint rejects its requests, usually a missing or wrong auth check on your side. Confirm what your endpoint expects and make sure Intercom's requests satisfy it, or exempt the webhook path from auth and verify the payload signature instead.

Not specified by the original author.

TL;DR

Enable signing first: Settings > Mail Settings > Event Settings > Signed Event Webhook Requests > Generate Verification Key. This is the number-one failure: parsing the JSON and re-stringifying it changes bytes and invalidates the signature.

Steps

1. Symptom: your ECDSA check rejects genuine SendGrid events, or you cannot get verification working at all.
2. Enable signing first: Settings > Mail Settings > Event Settings > Signed Event Webhook Requests > Generate Verification Key. No key, no signature headers.
3. Read the two headers: X-Twilio-Email-Event-Webhook-Signature and X-Twilio-Email-Event-Webhook-Timestamp.
4. Hash sha256 over the timestamp bytes followed by the RAW payload bytes. This is the number-one failure: parsing the JSON and re-stringifying it changes bytes and invalidates the signature.
5. Base64-decode the signature, ASN.1 unmarshal into the {r, s} pair, and ECDSA-verify against the public key.
6. Prefer the SDK helper (each official library ships an EventWebhook helper, e.g. the eventwebhook package) over hand-rolled crypto.
7. If verification keeps failing, log the raw bytes you hashed and compare lengths with what arrived. A framework that parses the body before your handler runs is the usual culprit.

When to use

You are seeing this: Symptom: your ECDSA check rejects genuine SendGrid events, or you cannot get verification working at all. Use this skill when you run into "SendGrid Event Webhook signature verification failures".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

The official Event Webhook security doc: Twilio signs with an ECDSA key pair; the signature arrives in X-Twilio-Email-Event-Webhook-Signature and the timestamp in X-Twilio-Email-Event-Webhook-Timestamp. Verification: base64-decode the signature, ASN.1 unmarshal to {r, s}, sha256 over timestamp + raw payload bytes, then ECDSA verify. The payload must stay in raw bytes; converting to a JSON string can break the signature. SDKs ship EventWebhook helpers. Sources: https://github.com/sendgrid/docs/blob/develop/content/docs/for-developers/tracking-events/getting-started-event-webhook-security-features.md