From the Library of Congress:
Systems of the United States Copyright Office are back online as of 8:00 am, Sunday, September 6, 2015 and customers may resume submitting registration applications electronically.
As previously reported, on Friday, August 28th, the Library of Congress shut down a data center that hosts a number of agency technology systems, including the Copyright Office’s electronic registration program. This was done to accommodate a two-day annual power outage scheduled by the Architect of the Capitol, which owns and maintains Library buildings. On Sunday, August 30th, the Library attempted to reopen the data center, but was unable to bring copyright systems and other agency functions online as planned. Both Library and Copyright Office staff have since worked around the clock to assess problems and solutions and ensure the ongoing integrity of Copyright Office data.
Thank you for your ongoing patience.