I installed a public SSL certificate on an ER-X using the procedure documented here, while running firmware v1.9.0.
After upgrading to v1.9.1, lighttpd fails to start because the /etc/ssl/server.pem and /etc/ssl/intermediate.crt files are missing:
root@gw:/etc/lighttpd# lighttpd -f lighttpd.conf
2016-12-19 17:53:45: (network.c.537) SSL: BIO_read_filename('/etc/ssl/server.pem') failed
2016-12-19 18:06:10: (network.c.734) SSL: error:02001002:system library:fopen:No such file or directory /etc/ssl/intermediate.crt
2016-12-19 18:06:10: (network.c.873) SSL: error:20074002:BIO routines:FILE_CTRL:system lib /etc/ssl/intermediate.crt
How can I preserve my public SSL certificate during firmware updates?