If you have an editing event scheduled during the next 24 to 36 hours, please note this potential problem from yesterday's Tech News:

Only a limited number of accounts can be created from one IP address. An IP address can be whitelisted so that it can create as many accounts as needed. This is useful at events where many new persons learn to edit. IP addresses that are whitelisted for this reason will also not show CAPTCHAs when you create accounts. This will happen on Wednesday. https://phabricator.wikimedia.org/T227487

If you have an event scheduled, you can work around this by asking people to create their accounts at home (and bring their new usernames and passwords with them), or by requesting an exemption for your event (I think any local admin can do this, but you'll need to know the IP addresses at your venue).