On November 7, 2017, the IMSLP received a cease and desist letter from the heirs of Sergei Prokofiev expressing concern that the composer's music was available for download in countries where his music was still under copyright protection. This demand was followed up by a separate letter from the National Music Publishers Association on January 19, 2018. On February 23, 2018, access to all compositions by Prokofiev was blocked by the IMSLP in response to these legal threats. The issues were partially resolved on the IMSLP forums in July 2018, resulting in the reupload of Prokofiev's pre-1923 works. In August, the remainder of Prokofiev's works were reuploaded so that they would only be available in the countries they are allowed in.