Slack error ekm_access_denied: Admins have disabled messaging here (EKM)

The workspace runs Slack's Enterprise Key Management (EKM), and its administrators have suspended posting in the target conversation — typically by revoking encryption key access for that channel or team as part of a security response. The chat.postMessage reference documents it as "Administrators have suspended the ability to post a message."

EKM lets Enterprise Grid organizations control their own encryption keys; revoking key access is the mechanism admins use to freeze data access during incidents, legal holds, or offboarding events. While a revocation is in force, nobody — humans or apps — posts to the affected conversations, and API calls fail with this string. Your integration is collateral, not the target.

There is nothing to fix in code. The error clears when the organization's admins restore key access. What your app should do is degrade gracefully: recognize the string, stop hammering the affected channel, and surface a clear message to the customer that their own organization's key management is blocking delivery — a materially different support conversation from "the bot is broken".

{"ok": false, "error": "ekm_access_denied"}

For apps sold into Enterprise Grid organizations, build EKM awareness into error handling from the start: treat ekm_access_denied as a distinct, customer-side policy state with its own alerting and messaging. Avoid retry storms against frozen channels — they burn rate limit budget without any chance of success.