If you see this, check your logs, I found this in mind, it was php-pdo missing. Actually it was not missing, but httpd had not been restarted since it was installed.
[Thu Mar 09 02:49:16.682471 2017] [:error] [pid 3611] [client 192.168.88.245:34266] {"reqId":"WMC0nFFrJ-GCwZGoc2zWYQAAAAo","remoteAddr":"192.168.88.245","app":"index","message":"Exception: {\\"Exception\\":\\"Error\\",\\"Message\\":\\"Class 'PDO' not found\\",\\"Code\\":0,\\"Trace\\":\\"#0 \\\\\\/var\\\\\\/www\\\\\\/html\\\\\\/nextcloud\\\\\\/lib\\\\\\/private\\\\\\/Setup.php(171): OC\\\\\\\\Setup->getAvailableDbDriversForPdo()\\\\n#1 \\\\\\/var\\\\\\/www\\\\\\/html\\\\\\/nextcloud\\\\\\/lib\\\\\\/private\\\\\\/legacy\\\\\\/util.php(658): OC\\\\\\\\Setup->getSupportedDatabases()\\\\n#2 \\\\\\/var\\\\\\/www\\\\\\/html\\\\\\/nextcloud\\\\\\/lib\\\\\\/base.php(692): OC_Util::checkServer(Object(OC\\\\\\\\AllConfig))\\\\n#3 \\\\\\/var\\\\\\/www\\\\\\/html\\\\\\/nextcloud\\\\\\/lib\\\\\\/base.php(1092): OC::init()\\\\n#4 \\\\\\/var\\\\\\/www\\\\\\/html\\\\\\/nextcloud\\\\\\/index.php(38): require_once('\\\\\\/var\\\\\\/www\\\\\\/html\\\\\\/n...')\\\\n#5 {main}\\",\\"File\\":\\"\\\\\\/var\\\\\\/www\\\\\\/html\\\\\\/nextcloud\\\\\\/lib\\\\\\/private\\\\\\/Setup.php\\",\\"Line\\":115}","level":3,"time":"2017-03-09T01:49:16+00:00","method":"GET","url":"\\/nextcloud\\/index.php","user":"--","version":""}