Channels
Delivery troubleshooting
Diagnose messages that fail to send or arrive, read the send-failure reference number, and find the cause and fix for each channel with a symptom table.
Last updated: 2026-09-29
When a reply does not reach a customer, or a customer's message does not reach you, the cause is nearly always one of a few things: a channel rule (such as the 24-hour window), a disconnected or expired channel connection, a provider setup problem, or a workspace state such as read-only. This page shows how to tell which, and how to fix it.
First checks#
Work through these in order before anything channel-specific.
- Is the conversation open? Closed conversations cannot send. Reopen it or wait for the customer's next message.
- Is the workspace read-only? Sending is refused with a workspace read-only error when the account is read-only, for example after a lapsed subscription. See Plans and billing.
- Is the channel connected? Open Settings, Workspace setup, Integrations. A card that says Needs attention or Disconnected means the connection must be repaired.
- Is the reply window open? On WhatsApp, Messenger and Instagram, the conversation details panel shows a Service window countdown.
- Did the operator send it? AI replies that never appear are usually a gate problem, not a delivery problem. See How the AI works and Conversation control.
The failed-send banner and reference number#
When an operator's reply is refused, the inbox shows a banner with a 16-character Reference (رقم المتابعة in Arabic). Copy it when you contact support.
- The reference is derived from your workspace, the conversation and the message, so retrying the same message shows the same reference.
- The web and mobile apps both record each failed attempt against that reference, up to 20 attempts per reference.
- The banner's message tells you what to do. A deliberate refusal (window ended, conversation read-only, another agent holds the reply, capacity, duplicate request) carries its own code and explanation.
- A generic failure with code
SEND_ENQUEUE_FAILEDmeans an unexpected error inside Sela. Contact support with the reference. Sela's team can look the reference up and see the operator, conversation, channel, attempt number and error details.
Admins and supervisors can also see recent failures for their workspace from the dashboard's diagnostics. Do not include customer message text or phone numbers when you share diagnostics; the reference is enough.
Refusals you can fix yourself#
| Message or code | Meaning | Fix |
|---|---|---|
| The 24-hour Meta reply window has ended | The customer's last message is over 24 hours old (WhatsApp, Messenger, Instagram) | WhatsApp: send an approved template or broadcast. Messenger and Instagram: wait for the customer to write. |
| Conversation is read-only (closed, WhatsApp disconnected or inactive, imported archive, no longer bound to a connection) | The thread cannot send | Reopen or reconnect the channel. Imported archive threads reopen when the customer writes. |
| Telegram conversation is read-only | Telegram refused sends to that chat, for example the customer blocked the bot | Nothing to fix. Wait for the customer to write again. |
| Native reply unavailable (Instagram) | Instagram would not accept a quoted reply | Send the reply without quoting. |
| Workspace read-only | Account state | Restore the subscription or ask the account owner. |
| Email or SMS: channel disabled or key missing | Channel switched off or credentials incomplete | Check the Email or SMS page. |
Per-channel causes and fixes#
WhatsApp#
| Symptom | Likely cause | Fix |
|---|---|---|
| Free-form reply refused | 24-hour window ended | Use a template or broadcast. See WhatsApp. |
| Template send not accepted | Template not approved, or the category was changed by Meta | Check its status on the WhatsApp page Templates tab. |
| Send blocked, balance | Balance too low to reserve funds (Our Partner) | Top up balance on the WhatsApp page. Held funds are released when a send fails. |
| Customer messages stop | Connection needs attention or was removed on the phone (coexistence) | Reconnect from Integrations, or Reconnect original number for coexistence. |
| Old messages missing | Coexistence history only covers 180 days of one-to-one chats | Expected. Media older than about 14 days may be unavailable. |
| Link code path: link revoked | The sender was unlinked | Re-link via OTP Platform with a new code. |
| AI does not answer a late message | Delayed messages are kept in history without an AI reply | Reply manually. |
Messenger and Instagram#
| Symptom | Likely cause | Fix |
|---|---|---|
| Card shows Needs attention | Access token invalidated (password change, removed permission) | Reconnect from Integrations. |
| Wrong Page receiving messages | Only the first Facebook Page is connected | See Messenger and Instagram. |
| No reply to a comment | Comments are not handled | Reply in Facebook or Instagram directly. |
| Attachment not sent on Instagram | Documents are not supported there | Send an image, video or audio, or a link. |
Telegram#
| Symptom | Likely cause | Fix |
|---|---|---|
| "Telegram needs attention" | Token revoked or webhook replaced by another service | Check connection, then Reconnect. |
| Messages stop for everyone | Bot disconnected or replaced | Reconnect the bot. |
| Only one chat fails | The customer blocked the bot or deleted the chat | Nothing to fix. |
| Reaction fails | Emoji outside Telegram's allowed list | Choose another emoji. |
See Telegram. Sela retries a rate-limited Telegram send once after the wait Telegram asks for. It does not automatically retry a send whose outcome is unclear, so nothing is sent twice.
Email#
| Symptom | Likely cause | Fix |
|---|---|---|
| Nothing arrives | Resend webhook missing or wrong URL | Recreate the email.received webhook. |
| Resend reports 401 | Wrong signing secret | Update the Webhook Signing Secret. |
| Resend reports 404 | Recipient does not match the saved inbound address | Correct Inbound Email Address. |
| Replies do not thread | Missing reply headers on the original | New replies thread normally. |
SMS#
| Symptom | Likely cause | Fix |
|---|---|---|
| Nothing arrives | Twilio webhook not set or not POST | Paste the Inbound SMS Webhook URL in Twilio. |
| Twilio reports 401 | Auth Token mismatch | Re-enter the Auth Token. |
| Twilio reports 404 | Number unknown or SMS disabled | Check the number format and SMS Enabled. |
| Message cut into parts | Long text is split into up to 3 messages | Keep replies short. |
See Email and SMS.
Web chat and media#
| Symptom | Likely cause | Fix |
|---|---|---|
| Customer cannot attach files | The attach button appears only after a chat is escalated to a human | Expected while the AI handles the chat. |
| Upload times out | Slow network | The widget shows "Media upload timed out. Please try again." Try again. |
| Media looks missing on WhatsApp | Media may not be available from the source | Ask the customer to resend. |
Details for the widget are in Web chat widget. Calls have their own causes; see Calls.
Symptom, cause, fix#
| Symptom | Most likely cause | Fix |
|---|---|---|
| Reply banner with a reference and "24-hour window" | Window ended | Template (WhatsApp) or wait for the customer |
Reply banner with SEND_ENQUEUE_FAILED | Unexpected Sela error | Send the reference to support |
| Reply refused, conversation read-only | Closed, disconnected or archived thread | Reopen or reconnect |
| Reply refused, workspace read-only | Lapsed or restricted account | Restore the plan |
| Card says Needs attention | Expired or revoked connection | Reconnect the channel |
| No messages coming in on one channel | Webhook or connection issue at the provider | Check provider webhook and card status |
| AI silent but messages arrive | AI gate | Check credits, assistant profile, status |
| Only voice notes fail | Media Understanding off | Enable it under Widget settings |
| Calls connect but have no audio | No network relay | See Calls |
Webhook health#
Providers send events to Sela through webhooks, and Sela checks each request's signature. A wrong secret, a mismatched app or environment, or a repeated request appears as a 401 or 400 in the provider's delivery log. Fix the secret or URL on the provider side. Sela also removes stale webhook deliveries in the background and re-tries failed Telegram inbound events on a schedule.
Outbound webhooks that Sela sends to your servers are separate. An endpoint is disabled automatically after 10 consecutive deliveries that exhaust their retries, and a banner appears. See Webhooks.
When to contact support#
Contact support if the failure persists after the fixes above, or if you see SEND_ENQUEUE_FAILED. Give the 16-character reference, the channel, the approximate time and what you already tried. See Troubleshooting for general help.
Can't find what you need? Contact support.