Slack error cant_update_message: Not allowed to update this message
Last verified against Slack API reference - chat.postMessage errors
Authenticated user does not have permission to update this message.What error cant_update_message means
The message exists, but the identity behind your token is not allowed to edit it. chat.update documents it as "Authenticated user does not have permission to update this message." Slack's edit model is strict about authorship: a bot token edits the bot's own messages; a user token edits that user's messages (subject to workspace edit settings). Trying to edit somebody else's message — another app's, another user's, a system message — lands here regardless of scopes.
The common integration shape that triggers it: the message was posted by one identity and the edit is attempted by another. An incoming-webhook message edited via the Web API token, a message posted with a user token but edited with the bot token, or two environments' bots sharing a channel and each trying to maintain the other's status message. The (channel, ts) you stored may be perfectly correct — the author is what does not match.
Also nearby on the same method: edit_window_closed when workspace settings time-limit edits, and is_inactive ("The message cannot be edited within a frozen, archived or deleted channel"). If you cannot edit as the original author, the fallback pattern is delete-and-repost when you own deletion rights, or posting a follow-up/thread reply when you do not.
What it looks like
{"ok": false, "error": "cant_update_message"}Why it happens
- The edit uses a different identity (token) than the one that posted the message.
- The target message belongs to a human user or another app.
- Workspace message-editing settings restrict edits for the authenticated user.
- The message is a system/subtype message that cannot be edited.
How to fix Slack error cant_update_message
- 1Confirm authorship: compare the message's bot_id/user with your token's identity from auth.test.
- 2Perform edits with the same token that created the message; keep the posting identity recorded with the (channel, ts).
- 3If editing another identity's message is genuinely required, redesign: post-and-maintain your own status message instead.
- 4Where edit rights are absent, fall back to a threaded correction or delete-and-repost with the owning token.
How to stop it recurring
Record which identity posted every message your app may later mutate, and route mutations through that same identity. Keep one owner per maintained message (status boards, live dashboards) so cross-identity edits never arise.
Official reference: Slack API reference - chat.postMessage errors. See all Slack error codes or the Slack limits and quotas.
Related codes
- message_not_found: No message at that timestampNo message exists with the requested timestamp.
- edit_window_closed: The edit window has closedThe message cannot be edited due to the team message edit settings
- cant_delete_message: Not allowed to delete this messageAuthenticated user does not have permission to delete this message.
Error cant_update_message - quick answers
What does Slack error cant_update_message mean?
The message exists, but the identity behind your token is not allowed to edit it. chat.update documents it as "Authenticated user does not have permission to update this message." Slack's edit model is strict about authorship: a bot token edits the bot's own messages; a user token edits that user's messages (subject to workspace edit settings).
How do I fix Slack error cant_update_message?
1. Confirm authorship: compare the message's bot_id/user with your token's identity from auth.test. 2. Perform edits with the same token that created the message; keep the posting identity recorded with the (channel, ts). 3. If editing another identity's message is genuinely required, redesign: post-and-maintain your own status message instead. 4. Where edit rights are absent, fall back to a threaded correction or delete-and-repost with the owning token.
Stop debugging Slack by hand
Connect the channel through Conferbot: tokens, webhooks and retries are handled, failures show as readable status.