91007: Unexpected loss of presence membership

The connection was removed from the presence set despite still being active, so the channel was detached to prompt the Ably SDK to automatically re-enter presence. The condition is usually transient.

What you should do

Usually nothing. A client that entered presence re-enters it automatically after this error: the channel detaches, re-attaches, and the member rejoins the presence set without any action.

There is nothing in your application to change, because the cause is internal to Ably rather than your configuration. If this error is having a negative impact on your application, report it to Ably.

Why it happens

During routine changes on Ably's side, such as a failover or a rebalancing of capacity, a presence member can be dropped from the presence set even though its connection is still active. Ably detects the inconsistency and detaches the channel so the client re-attaches and re-enters presence, restoring the member.

What you'll see

The channel is detached and then re-attached, and the connection re-enters presence; published messages and other channels are unaffected. The error is reported with code 91007 and HTTP status 500, with the message Unexpected loss of presence membership information for this connection, requesting reattach to trigger automatic presence reentry.