lighttpd 500 error Turn off xcache，Close fastCGI
Although the default is not turned xcache kloxo，But sometimes not careful on the，Unknowingly opened xcache。If it turns xcache，lighttpd 500 error please try to close xcache。
If not enough，Fastcgi try again Close。
Not enough，You can also try adding a few more lighttpd process method：In LIGHTTPD.CONF which added：
server.max-worker = 6
# max-connections == max-fds/2 (maybe /3)
server.max-connections = 1024
server.max-fds = 2048
#Maximum number of seconds until an idling keep-alive connection is dropped.
server.max-keep-alive-idle = 5
server.max-keep-alive-requests = 1000
