At 1AM PT June 16, 2016 the Lab will be working on a cluster of utility servers. This means the SL system will be unstable during that time. Users served by the servers being worked on will likely be disconnected and those attempting to login will not be able to. Others may have chat, and group chat issues.
Follow the Linden Twitter feed at @SLGridStatus.
There is no ETA for return to service.