After careful consideration the Steering Committee of MTNS has made the decision to cancel the postponed conference which was due to be held in August 2021. The arrangements negotiated with our co-sponsor IFAC and announced in Author Information on 17 May 2020 now come into force. Final versions of full papers that were notified as being accepted in May 2020 may be uploaded without further review and will be published in IFAC papers online, with a condition from IFAC that they are not substantially different from the accepted version. As announced on 17 May 2020, accepted extended abstracts will no longer be published or posted on the conference website. The timetable and instructions for upload of full papers will be confirmed shortly under Author Information together with the paper upload fee. Participants are advised that it is necessary to charge an upload fee in order to cover costs incurred. We hope to open the submission site for full paper uploads on 1 April 2021 with a provisional closing date of 15 April 2021. Yours sincerely, Malcolm Smith and Rodolphe Sepulchre.