I did check all the input files, and tehy they do exist. looking at code, I do see this error only in: contrib/libosmium/include/osmium/io/detail/read_write.hpp: throw std::system_error{errno, std::system_category(), std::string("***Open failed for*** '") + filename + "'"}; but I don't understand why user "osm" is view as file .. the function "open_for_writing" is called by: contrib/libosmium/include/osmium/io/writer.hpp: by function in *contrib/libosmium/include/osmium/io/writer.hpp*: std::unique_ptr<osmium::io::Compressor> compressor = **CompressionFactory::instance().create_compressor**(file.compression(), osmium::io::detail::open_for_writing(***m_file.filename()***, options.allow_overwrite), options.sync);

I did check all the input files, and tehy do exist. looking at code, I do see this error only in: contrib/libosmium/include/osmium/io/detail/read_write.hpp: throw std::system_error{errno, std::system_category(), std::string("***Open failed for*** '") + filename + "'"}; but I don't understand why user "osm" is view as file .. the function "open_for_writing" is called by: contrib/libosmium/include/osmium/io/writer.hpp: std::unique_ptr<osmium::io::Compressor> compressor = **CompressionFactory::instance().create_compressor**(file.compression(), osmium::io::detail::open_for_writing(***m_file.filename()***, options.allow_overwrite), options.sync);