After upgrade the host system to 16.04, and upgrade PHP5 to PHP7, it occur the following errors

data) in /var/www/dokuwiki/wiki/lib/plugins/code/syntax/code.php on line 33
PHP message: PHP Fatal error:  Uncaught Error: Call to undefined function utf8_decode() in /var/www/dokuwiki/wiki/inc/utf8.php:228
Stack trace:
#0 /var/www/dokuwiki/wiki/inc/parser/metadata.php(104): utf8_substr('Tools\n\nIP Locat...', 0, 500)
#1 /var/www/dokuwiki/wiki/inc/parserutils.php(495): Doku_Renderer_metadata->document_end()
#2 /var/www/dokuwiki/wiki/inc/parserutils.php(270): p_render_metadata('tools', Array)
#3 /var/www/dokuwiki/wiki/inc/common.php(245): p_get_metadata('tools')
#4 /var/www/dokuwiki/wiki/doku.php(91): pageinfo()
#5 {main}
  thrown in /var/www/dokuwiki/wiki/inc/utf8.php on line 228" while reading response header from upstream, client: 140.207.23.59, server: wiki.pjq.me, request: "GET /doku.php?id=tools HTTP/1.1", upstream: "fastcgi://unix:/run/php/php7.0-fpm.sock:", host: "wiki.pjq.me", referrer: "http://wiki.pjq.me/doku.php?id=start"

After some google, install php7.0-xml will fix it.

apt-get install php7.0-xml

• http://stackoverflow.com/questions/35701730/utf8-endecode-removed-from-php7