# Block Users API guide | Developer Documentation

<div id="bkmrk-block-users-api-guid">## Block Users API guide

<div><span>Updated: Feb 23, 2026</span></div><div>The Block Users API enables your business to block bad actors from contacting you.</div><div id="bkmrk-how-it-works"><div id="bkmrk-how-it-works-1"><div>### How it works

</div></div></div><div>When you block a WhatsApp user, the following happens:</div><span>The user cannot contact your business or see that you are online.</span><span>Your business cannot message the user. If you do, you will encounter an error.</span><div>Errors on the API occur per-number since blocks might succeed on some numbers and fail on others.</div><div>The Block Users API is synchronous.</div><div id="bkmrk-limitations"><div id="bkmrk-limitations-1"><div>### Limitations

</div></div></div><span>You can only block users that have messaged your business in the last 24 hours.</span><span>You cannot use this API to block another WhatsApp Business account.</span><span>The blocklist has a 64,000 user limit.</span><div id="bkmrk-features"><div id="bkmrk-features-1"><div>### Features

</div></div></div><div>The API contains three endpoints:</div><div id="bkmrk-error-codes"><div id="bkmrk-error-codes-1"><div>### Error codes

</div></div></div><div><table><thead><tr><th><span>Code </span></th><th><span>Description </span></th></tr></thead><tbody><tr><td><div><div>`139100`</div><div>Failed to block/unblock some users</div></div></td><td><div><div>Bulk blocking failed to block some or all of the users.</div></div></td></tr><tr><td><div><div>`139101`</div><div>Blocklist limit reached</div></div></td><td><div><div>The blocklist has reached its 64,000 user limit.</div></div></td></tr><tr><td><div><div>`139102`</div><div>Blocklist concurrent update</div></div></td><td><div><div>Occurs when the blocklist is updated while performing a pagination request and `version_id` does not match.</div></div></td></tr><tr><td><div><div>`139103`</div><div>Internal error</div></div></td><td><div><div>Internal error, please try again.</div></div></td></tr><tr><td><div><div>`130429`</div><div>Rate Limit Hit</div></div></td><td><div><div>Occurs when either:</div><span>Too many numbers are in the request itself.</span><span>Or, too many requests are made over a short period of time.</span></div></td></tr><tr><td><div><div>`131021`</div><div>Self Block</div></div></td><td><div><div>Failed to block self phone number.</div></div></td></tr><tr><td><div><div>`131047`</div><div>Re-engagement required</div></div></td><td><div><div>Occurs if the business has not received a message from that number in the last 24 hours.</div><div>This error will also be returned if the number is an invalid WhatsApp user.</div></div></td></tr></tbody></table>

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