(FILES) In this file photo taken on July 7, 2017 German Chancellor Angela Merkel greets Turkey's President Recep Tayyip Erdogan at the beginning of the G20 meeting in Hamburg, northern Germany. - Turkish President Recep Tayyip Erdogan will pay a state visit to Germany from September 27 to 29, 2018, as the two countries seek to rebuild ties after a series of sharp spats but the controversial trip is likely to be overshadowed by protests (Photo by John MACDOUGALL / various sources / AFP)