ERR_NGROK_SHIP_POOL_JOIN_KEY_ALREADY_EXISTS: A pool with this join key already exists on this account - ngrok documentation

What does ERR_NGROK_SHIP_POOL_JOIN_KEY_ALREADY_EXISTS mean?

ngrok returns ERR_NGROK_SHIP_POOL_JOIN_KEY_ALREADY_EXISTS with this message:

A pool with this join key already exists on this account.

Where can I get more help with ERR_NGROK_SHIP_POOL_JOIN_KEY_ALREADY_EXISTS?

Email support@ngrok.com and include the error code.