I have been getting this error since yesterday and I was wondering if it was a general problem or just me. I have tried mirrors and changes of ports.
Error in listMarts(host = host, path = path, port = port, includeHosts = TRUE, : Unexpected format to the list of available marts. Please check the following URL manually, and try ?listMarts for advice. http://www.ensembl.org:80/biomart/martservice?type=registry&requestid=biomaRt