Every Twilio error code diagnosed and fixed. SMS, voice, WhatsApp, webhook, and API errors with step-by-step solutions from consultants who debug these in live production systems.
Get Emergency Twilio SupportTwilio error codes are 5-digit numbers organized into ranges that map to specific product areas. SMS delivery errors start with 30xxx, REST API errors with 20xxx, TwiML and webhook errors with 11xxx and 12xxx, Voice call errors with 13xxx and 31xxx, and WhatsApp channel errors with 63xxx. Knowing the range tells you which product is failing and which Console section to look at first, before you read a single line of documentation.
Every guide in this library follows the same structure: what the error code means, what specifically causes it (with the exact Console navigation path to verify), how to fix it step by step, how to prevent it from recurring, and when the complexity warrants escalating to a specialist. The goal is that a developer who has never seen a particular error code can open the guide, follow the steps, and have the error resolved within the hour without needing to search through API documentation or open a support ticket.
These guides are written by consultants who debug Twilio errors in live production systems, not from documentation alone. The specific Console paths, API parameters, and carrier behavior described in each guide reflect what actually works in production, including the edge cases and undocumented behaviors that official documentation does not cover. Updated June 2026 to reflect current 10DLC registration requirements, WhatsApp Business API template approval processes, and Twilio Voice SDK error handling changes.
Your message queue is full. Here is exactly why Twilio error 30001 fires and how to drain the queue and prevent it from blocking your messages again.
A suspended Twilio account stops every message instantly. Here is what triggers error 30002, how to get reinstated fast, and how to prevent it.
The destination handset cannot be reached. Here is what error 30003 means, why carriers return it, and what you can do to reduce its frequency.
Your message was blocked before delivery. Error 30004 is one of the most common and most misunderstood Twilio errors. Here is the full diagnosis.
Twilio cannot identify the destination handset. Error 30005 usually means a bad number or a ported number with stale carrier data.
You tried to send SMS to a landline or a number on an unreachable carrier. Here is how to detect and filter these numbers before they cost you money.
Carrier filtering is the silent killer of SMS campaigns. Error 30007 means your message was blocked at the carrier level. Here is the full fix.
Error 30008 is a catch-all carrier error with no specific code returned. Here is how to diagnose it and reduce its occurrence in your send logs.
A multipart SMS is missing one or more segments on the inbound side. Here is what causes error 30009 and how to handle segmented messages correctly.
Your MaxPrice parameter is set too low for the destination. Here is how to fix error 30010 without overpaying for international messages.
Your MMS or SMS content is too large for the carrier to deliver. Here is the size breakdown by carrier and how to fix error 30019 permanently.
You are sending too fast for the carrier to accept. Error 30020 is a rate limiting error that kills bulk campaigns. Here is how to fix your throughput.
The carrier failed the message but gave no reason. Error 30021 is frustrating because there is no obvious fix. Here is how to diagnose it anyway.
Your A2P 10DLC campaign has hit its throughput ceiling. Error 30022 means messages are being dropped. Here is how to increase your limits.
You have hit your daily message cap for your 10DLC campaign. Error 30023 stops all sending until midnight. Here is how to raise your cap.
The numeric sender ID you are using has not been provisioned for the destination country. Here is how to provision it correctly.
Your number is not provisioned for A2P 10DLC or the destination is out of coverage. Here is the exact fix for error 30026.
T-Mobile has blocked further messages from your campaign today. Error 30027 is T-Mobile specific. Here is what to do until the limit resets.
Sole proprietor 10DLC registrations have strict daily caps. Error 30028 means you have hit yours. Here is how to manage volume within the limit.
Your toll-free number is not verified for A2P sending. Carriers block unverified toll-free traffic. Here is how to complete verification fast.
You are sending A2P traffic from a number that is not registered to a campaign. Error 30034 is entirely preventable. Here is the fix.
Your number has no campaign registration attached. Error 30035 blocks all A2P traffic from that number until registration is complete.
The message validity period expired before the carrier could deliver it. Error 30036 usually points to a queue backup or a validity setting that is too short.
The carrier is experiencing an outage and cannot deliver your message. Error 30037 is outside your control but there are things you can do to mitigate it.
The carrier rejected your message content as a policy violation. Error 30038 is serious. Here is what content triggers it and how to clean your messages.
Your MMS media file is too large. Error 11751 blocks MMS delivery entirely. Here is the size limit breakdown and how to compress media correctly.
The To number you passed is not a valid phone number. Error 21211 is one of the most common Twilio API errors and is always fixable in your code.
The From number is invalid or not owned by your account. Error 21212 stops message sending at the API level before anything reaches a carrier.
Twilio cannot reach the To number you specified. Error 21214 is different from a carrier delivery failure. Here is the exact distinction and fix.
The number format is unrecognizable to Twilio. Error 21217 almost always means a formatting issue in how you are passing the number to the API.
Trial accounts can only send to verified numbers. Error 21219 is a trial restriction. Here is how to verify numbers and when to upgrade.
Your account does not have geographic permissions for the destination country. Error 21408 blocks international sending until you enable the region.
The number you are sending from cannot send SMS. Error 21606 means you picked a voice-only number or a number without SMS capability.
The recipient has opted out by replying STOP. Error 21610 is a hard block. Sending to opted-out numbers violates TCPA. Here is how to handle it.
You have too many messages queued on a single From number. Error 21611 means you need to distribute send volume across a number pool.
The specific combination of your From number and the To number is not allowed. Error 21612 is a routing restriction. Here is the fix.
The To number is not a mobile number and cannot receive SMS. Error 21614 fires when you try to send to a landline without MMS fallback.
Your message body is too long. Error 21617 fires before the message even reaches a carrier. Here is the character limit breakdown and fix.
SMS permissions are not enabled on your account or subaccount. Error 21408b is an account-level restriction. Here is how to enable SMS sending.
Your API credentials are wrong or missing. Error 20003 is an authentication failure at the API gateway level. Here is how to diagnose and fix it fast.
The resource you are trying to access does not exist in your account. Error 20404 is a 404 at the Twilio API level. Here is what causes it.
You are hitting Twilio API rate limits. Error 20429 means requests are being rejected. Here is how to implement proper backoff and queuing.
One of the parameters you passed to the API has an invalid value. Error 20422 is always a code-side issue. Here is how to identify the bad parameter.
Twilio cannot reach your webhook URL. Error 11200 means your server is down, your URL is wrong, or a firewall is blocking Twilio. Here is the full fix.
Twilio connected to your server but the connection failed before a response was received. Error 11205 points to timeout or SSL issues.
Your webhook returned a response that violates HTTP protocol. Error 11206 is always a server-side issue. Here is what Twilio expects and how to fix it.
Twilio cannot resolve the hostname in your webhook URL. Error 11210 means a DNS failure or a typo in your webhook configuration.
Your webhook URL is redirecting too many times. Error 11215 fires when Twilio follows more than 10 redirects. Here is how to fix your redirect chain.
Twilio cannot parse the TwiML your webhook returned. Error 12100 means malformed XML. Here is how to validate and fix your TwiML response.
Your TwiML contains a verb or attribute that Twilio does not recognise. Error 12101 is a syntax error in your TwiML. Here is the full fix.
Your TwiML passed parsing but failed schema validation. Error 12200 is a warning that can become a blocker. Here is what to check and fix.
Your webhook returned the wrong Content-Type header. Error 12300 fires when Twilio receives anything other than text/xml or application/xml.
Twilio could not connect the outbound leg of your Dial verb. Error 13201 fires when the called party is unreachable or the number is invalid.
The caller ID you specified in your Dial verb is not valid or not owned by your account. Error 13214 blocks outbound calls entirely.
The phone number format inside your Dial verb is incorrect. Error 13223 is a TwiML formatting issue. Here is the correct E.164 format to use.
The number you are trying to dial is on a forbidden list. Error 13225 fires for premium rate numbers, restricted destinations, or sanctioned regions.
The Twilio Voice SDK encountered an unspecified error. Error 31000 is a catch-all that requires log analysis to diagnose. Here is the process.
The Voice SDK connection timed out before completing. Error 31003 usually points to network issues, firewall blocks, or incorrect ICE server configuration.
The Voice SDK failed to establish a connection. Error 31005 fires when WebRTC negotiation fails or signaling is interrupted.
The transport layer of the Voice SDK failed. Error 31009 means the WebSocket or media channel was dropped unexpectedly during a call.
The Voice SDK cannot access the microphone. Error 31201 is a browser permissions error. Here is how to fix it across Chrome, Firefox, and Safari.
The access token used to initialise the Voice SDK has expired. Error 31202 drops active calls and blocks new ones. Here is the token refresh fix.
Twilio cannot find a valid account matching the SIP credentials or trunk configuration. Error 31203 points to a misconfigured SIP domain or trunk.
The JWT token passed to the Voice SDK is malformed or uses incorrect claims. Error 31204 fires at SDK initialisation before any call is attempted.
Your JWT token has passed its expiry time. Error 31205 is similar to 31202 but fires at a different point in the SDK lifecycle. Here is the fix.
The user explicitly denied microphone access in their browser. Error 31208 cannot be fixed in code alone. Here is how to handle it gracefully in your UI.
The audio input device is unavailable or malfunctioning. Error 31402 fires when the selected microphone fails after initial permission was granted.
The audio output device cannot be accessed. Error 31403 fires when the speaker or headset fails during an active Voice SDK session.
The SIP endpoint returned a 480 Temporarily Unavailable response. Error 31480 means the called party exists but cannot accept calls right now.
The SIP endpoint returned a 486 Busy Here response. Error 31486 means the endpoint is active on another call or has rejected the call as busy.
The SIP endpoint returned a 603 Decline response. Error 31603 means the call was explicitly rejected, not just unanswered. Here is what triggers it.
Twilio cannot find the SIP trunk your call is referencing. Error 32011 fires when a trunk is deleted, misconfigured, or the SIP domain is wrong.
Authentication to your SIP trunk failed. Error 32017 fires when credentials are wrong, IP ACLs are misconfigured, or the trunk is suspended.
Twilio cannot find the WhatsApp recipient address you specified. Error 63003 fires when the To number is not a valid WhatsApp account.
WhatsApp rejected the content type you sent. Error 63005 fires when your message format does not match what WhatsApp allows in the current session.
No approved WhatsApp sender is available for your account. Error 63007 means your WhatsApp number is not approved or has been suspended.
Your message content violates WhatsApp Business messaging policies. Error 63013 is a serious policy violation that can get your number banned.
The 24-hour customer service window has expired. Error 63015 means you can no longer send freeform messages and must use an approved template.
You tried to send a freeform message outside an active session window. Error 63016 is a session management error. Here is how to handle it correctly.
You have exceeded the WhatsApp template message rate limit. Error 63018 throttles your sending until the rate window resets.
The parameters you passed to a WhatsApp template do not match the template definition. Error 63024 fires when variable counts or formats are wrong.
The template you are trying to send has not been approved by WhatsApp. Error 63051 blocks all sends using that template until approval is granted.
Twilio error logs contain everything you need to diagnose failures fast. Here is how to read them, filter them, and act on them without wasting time.
A practical reference to every major Twilio error code category, what each means, and where to start when you see one in your logs.
Your SMS shows sent but never arrives. Here is the complete diagnostic process for tracking down exactly where your message failed.
Voice calls failing silently is one of the hardest Twilio problems to diagnose. Here is a structured process that finds the cause every time.
Twilio can notify you the moment an error occurs. Here is how to configure error webhooks and alerts so you know about failures before your users do.
4XX errors are your fault. 5XX errors are Twilio or carrier side. Understanding this distinction cuts your debugging time in half.
Retrying failed messages without a strategy causes duplicate sends and carrier blocks. Here is the correct retry logic with idempotency keys.
The Twilio Debugger and App Monitor are the two most underused tools in the console. Here is how to use both to find errors in under 5 minutes.
Sent status does not mean delivered. Here is exactly what happens between Sent and Delivered and why messages disappear in that gap.
Undelivered is not one problem. It is twelve possible problems. This checklist walks you through every one in order of likelihood.
Status callbacks tell you exactly what happened to every message. Here is how to set them up, read them correctly, and act on each status value.
Silent filtering means your message shows Sent but was silently dropped by a carrier. It leaves no error code. Here is how to detect and fix it.
Twilio gives your webhook 15 seconds to respond. If it times out you get 502 or 504 errors. Here is how to fix slow webhooks before they break your app.
Invalid TwiML silently breaks calls and messages. Here is how to validate your TwiML before it hits production and fix the most common parse errors.
A 401 error means Twilio rejected your credentials. Here is how to find the right Account SID and Auth Token and fix 401 errors permanently.
Error 20429 means you are sending API requests faster than Twilio allows. Here is how to implement exponential backoff and request queuing correctly.
One party can hear but the other cannot. One-way audio is a NAT or firewall issue in most cases. Here is the full diagnostic and fix process.
Choppy audio means packet loss or jitter on the media path. Here is how to measure it, find the cause, and fix it at the network or codec level.
SIP registration failures stop all inbound calls to your SIP endpoint. Here is a structured process to diagnose and fix registration failures fast.
Trial accounts have hard restrictions that cause confusing errors. Here is every trial limitation, the error it causes, and how upgrading fixes it.
Answers to the questions we hear most from developers debugging Twilio errors.
The majority of Twilio error codes fall into four root causes. First, registration gaps: sending SMS from a 10DLC number without an approved Brand and Campaign registration causes 30007 (Carrier Violation) errors because carriers systematically filter unregistered A2P traffic. Second, format errors: phone numbers passed to the API without E.164 formatting (the plus sign followed by country code and subscriber number) produce 21211 or 13223 errors. Third, session mismanagement: attempting to send freeform WhatsApp messages after the 24-hour customer service window has closed produces 63015 and 63016 errors. Fourth, credential issues: using the Auth Token in the Account SID field, or using credentials from a different account, causes 20003 authentication errors. Each of these categories has a specific, repeatable fix.
A 30007 error caused by missing 10DLC registration takes 2 to 5 weeks to fully resolve because the fix requires completing A2P Brand registration through The Campaign Registry (typically 1 to 3 business days), then Campaign registration (typically 3 to 10 business days), then linking your Twilio numbers to the approved Campaign (same day). During this period, a toll-free number with verified opt-in documentation can serve as a compliant fallback sender for most use cases. If the 30007 is caused by content that violates carrier policies (SHAFT content, missing opt-out language, or misleading messaging), the fix is immediate after correcting the content, but any sender reputation damage from the violation takes additional weeks to recover.
Persistent 30007 (Carrier Violation) and 30004 (Message Blocked) errors at high volume can damage the sender reputation of a specific phone number or 10DLC Campaign, resulting in carriers applying long-term filtering to traffic from that number or Campaign even after the underlying issue is fixed. The recovery path is to stop sending from the affected number, complete or correct the 10DLC registration, replace the non-compliant content, and request a Campaign quality review through The Campaign Registry. For severe cases, retiring the affected number and starting fresh with a new number linked to a corrected Campaign is faster than attempting to rehabilitate a number with poor carrier standing. Acting on 30007 errors within 24 hours of first appearance minimizes reputation damage significantly.
The fastest diagnostic path is: navigate to the Twilio Console, go to Monitor, then Debugger, filter by the error code, and click the most recent entry for the full HTTP trace. The Debugger shows the exact request Twilio sent to your webhook, the response your server returned, and the Twilio-specific error code with its description. For delivery failures on SMS, also check Monitor, then Logs, then Messages and look at the ErrorCode field on the failed message record. The combination of the Debugger entry and the message log entry gives you the complete failure picture in under 2 minutes. If you need the root cause faster than that, our consultants can diagnose any error code in real time during a screen-share call.
Most Twilio error codes do not indicate a ban and are fully recoverable. Error codes 30003 through 30006 are carrier delivery failures affecting individual messages, not your account. Error code 20429 is a rate limit that resolves automatically when the rate window resets. Error code 63051 means a specific WhatsApp template is not yet approved, not that your account is restricted. The codes that do carry account-level risk are 30007 at sustained high volume (which can escalate to a carrier-level block on your number) and 63013 (WhatsApp policy violation, which can escalate to a WhatsApp Business Account suspension if repeated). Addressing these two codes immediately and correctly is the key to preventing account-level consequences.
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