Map Slack Web API errors for invalid auth, missing scopes, channel access, archived channels, app membership, message length, attachment limits, and rate limits. Use this reference to decide whether to reinstall Slack, invite the app, edit the message, or respect Retry-After.
Last updated: May 2026
9 documented error patterns across 5 categories
Clear guidance on reconnecting, retrying, replacing media, or changing content
Official platform references plus bundle.social production troubleshooting notes
Error categories
9 documented errors
All error codes
2 mapped cases
invalid_authReconnectSlack rejected the token.
Reconnect Slack or reinstall the app to create a valid bot token.
not_authedReconnectSlack did not receive authentication.
Send the correct Bearer token for the workspace.
1 mapped case
missing_scopeReconnectThe token lacks a required Slack scope.
Reinstall Slack with the needed chat, files, or conversation scopes.
3 mapped cases
channel_not_foundFix inputSlack could not find or access the channel.
Use a channel ID and invite the app to private channels before posting.
not_in_channelFix inputThe Slack app is not a member of the channel.
Invite the app to the channel or use chat:write.public for supported public-channel posting.
is_archivedFix inputThe target Slack channel is archived.
Choose an active channel or unarchive the channel before sending.
2 mapped cases
msg_too_longFix inputThe Slack message exceeds supported length.
Shorten the message or move long content into a file/snippet.
too_many_attachmentsFix inputThe Slack payload has too many attachments or blocks.
Reduce attachments, blocks, fields, or split the message.
1 mapped case
rate_limitedRetry laterSlack rate limited the Web API call.
Respect Retry-After and queue later sends.
Slack can reject messages because of length, too many blocks, too many attachments, invalid file fields, or malformed message structure. Shorten or simplify the payload before retrying.
Slack returns rate-limit responses and expects clients to wait before retrying. Immediate retries can worsen delivery delays.
Slack Web API calls can return HTTP 200 while still failing with ok: false. Always inspect the error value in the response body before assuming the message was delivered.
Slack messages can fail when the app is not invited to the channel, the channel is private, the channel is archived, the token is missing scopes, or the workspace installation changed.
bundle.social keeps Slack's ok/error response visible and separates failed sends by installation auth, missing scopes, channel membership, archived channels, message validation, and Retry-After handling.
Retry only temporary platform failures, processing delays, timeouts, 5xx responses, and rate-limit errors after the platform allows it. Do not retry the same request when the failure is caused by expired tokens, missing permissions, unsupported media, invalid captions, duplicate content, account restrictions, or policy blocks. The same payload will usually fail again until the account, media, content, or platform-specific setting is fixed.
Platform APIs change. Use these links to confirm current error behavior and field support.
Slack often returns HTTP 200 with ok false, so the JSON error value is the important signal. Read it together with workspace installation, channel membership, scopes, and Retry-After headers.
No. Reconnect or reinstall Slack for invalid_auth, not_authed, and missing_scope. For channel_not_found, not_in_channel, archived channels, long messages, too many attachments, or rate limits, fix workspace or message state first.
bundle.social keeps Slack's ok/error response available and makes it clear whether the failure is installation auth, missing scope, channel access, message shape, or rate limiting.
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